0001193125-24-125110 | 20-F | XBRL Viewer | Silicon Motion Technology Corp

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Consolidated Balance Sheets (Parenthetical) - $ / shares shares in Thousands	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Ordinary Shares, par value	$ 0.01	$ 0.01
Ordinary Shares, Authorized	500,000	500,000
Ordinary Shares, Issued	133,676	132,216
Ordinary Shares, outstanding	133,676	132,216

Long-Term Investments

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Long-Term Investments

6. LONG-TERM INVESTMENTS

As of December 31, 2022 and 2023, the Company held equity investments in several privately-held companies with the carrying value as follows:


	Percentage of Ownership						December 31
	2022			2023			2022		2023
							US$		US$
Non-marketable equity securities:
Cashido Corp . (Cashido)		0.6	%		0.6	%		—		—
Vastview Technology, Corp. (Vastview)		2.9	%		2.9	%		—		—
Kinara, Inc (Kinara)		14.1	%		14.1	%		6,500		6,500

								6,500		6,500
Marketable equity securities:
BIWIN Storage Technology Corp.(BIWIN)		0.3	%		0.3	%		2,767		10,616

								9,267		17,116

In June 2018, the Company invested US$3,000 thousand in the preferred stock of Kinara which is accounted for under the cost method. Kinara, previously known as Deep Vision, is a developer of

low-power

deep-learning processors. In March 2020 and May 2021, the Company invested US$2,000 thousand and

US$

1,500 thousand, respectively, in the preferred stock of Kinara.

In July 2021, the Company invested US$2,041 thousand in the common stock of BIWIN, which is a leading module maker in China focusing on solid state storage devices and is one of our customers and was listed on the Science and Technology Innovation Board of Shanghai Stock Exchange in December 2022. The Company had unrealized holding gains of US$896 thousand and US$8,002 thousand for the years ended December 31, 2022, and 2023, respectively.

Pension Plan - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accumulated benefit obligation			$ 162	$ 1,085
Employer contributions		$ 0	50	70
Subsequent Event [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer contributions	$ 0
SMI Taiwan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions and Recognized Pension Costs under Labor Pension Act		$ 3,369	$ 3,317	$ 2,652
Contributions Based on Percentage Employee Salaries under Labor Standards Law		2.00%
SMI Taiwan \| Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Percentage of Contribution by an Employer to Employees Pension		6.00%

Pension Plan

12 Months Ended

Dec. 31, 2023

Retirement Benefits [Abstract]

Pension Plan

11. PENSION PLAN

SMI Taiwan, the Company’s largest operating company, is a Taiwan registered company and subject to Taiwan’s Labor Pension Act (the “New Act”), which became effective on July 1, 2005, and the pension mechanism under the New Act is deemed a defined contribution plan. The employees who were subject to the Labor Standards Law prior to July 1, 2005 (the “Old Act”) could choose to be subject to the pension mechanism under the New Act or continue to be subject to the pension mechanism under the Old Act. For those employees who were subject to the Old Act and still work for the Company after July 1, 2005 and have chosen to be subject to the Old Act, their seniority as of July 1, 2005 were maintained. The New Act prescribes that the rate of contribution by an employer to employees’ pension accounts per month will not be less than 6% of each employee’s monthly salary. According to the New Act, SMI Taiwan made monthly contributions and recognized pension costs of US$2,652 thousand, US$3,317 thousand and US$3,369 thousand for the years ended December 31, 2021, 2022 and 2023, respectively.

The Company provides a defined benefit plan to the employees of SMI Taiwan under the Old Act that offers benefits based on an employee’s length of service and average monthly salary for the

six-month

period prior to retirement. The Company contributes an amount equal to 2% of salaries paid each month to a pension funds (the “Funds”), which is administered by the Labor Pension Fund Supervisory Committee established by the government (the “Committee”) and deposited in the Committee’s name in the Bank of Taiwan. Before the end of each year, the Company assesses the balance in the Funds. If the amount of the balance in the Funds is inadequate to pay retirement benefit for employees who conform to retirement requirements in the next year, the Company is required to fund the difference in one appropriation that should be made before the end of March of the next year. The government is responsible for the administration of all the defined benefit plans for the companies in Taiwan under the Old Act. The government also sets investment policies and strategies, determines investment allocation and selects investment managers. As of December 31, 2022 and 2023, the asset allocation was primarily in cash, equity securities and debt securities. Furthermore, under the Old Act, the rate of return on assets shall not be less than the average interest rate on a

two-year

time deposit published by the local banks. The government is responsible for any shortfall in the event that the rate of return is less than the required rate of return. However, information on how investment allocation decisions are made, inputs and valuation techniques used to measure the fair value of plan assets, the effect of fair value measurements using significant unobservable inputs on changes in plan assets for the period and significant concentrations of risk within plan assets is not fully available to the Company. Therefore, the Company is unable to provide the required fair value disclosures related to pension plan assets. Future contributions will be based on 2% of the employees’ annual salaries. As the benefits obligation has been fully funded, the Company contribution will be nil for the year ending December 31, 2024, which had been approved by the government on February 6, 2024.

For employees under defined contribution pension plans, pension costs are recorded based on the actual contributions made to employees’ individual pension accounts. For employees under defined benefit pension plans, pension costs are recorded based on actuarial calculations. Determining the cost associated with such benefits is dependent on various actuarial assumptions, including discount rate, expected return on plan assets, compensation increase, employee mortality and turnover rates. The Company reviewed its actuarial assumptions at the measurement date on December 31 every year. The effect of modifications to assumptions is recorded in accumulated other comprehensive loss and amortized to net periodic cost over future periods using the corridor method. The Company believes that assumptions utilized in recording its obligations under its plans are reasonable based on its experience and market conditions. Independent actuaries perform the required calculations to determine expense in accordance with U.S. GAAP. Actual results may differ from the actuarial assumptions and are generally accumulated and amortized into earnings over future periods. The net periodic costs are recognized as employees render services necessary to earn the benefits.

The changes in benefits obligation and plan assets and the reconciliation of funded status are as follows:


	December 31
	2021			2022			2023
	US$			US$			US$
Change in benefit obligation
Projected benefit obligation at beginning of year		1,716			1,803			244
Service cost		35			13			19
Interest cost		20			14			8
Actuarial loss (gain)		142			(205	)		(252	)
Benefits paid		(110	)		(1,236	)		—
Settlement		—			(145	)		—

Projected benefit obligation at end of year		1,803			244			19

Change in plan assets
Fair value of plan assets at beginning of year		1,551			1,639			552
Actual return on plan assets		48			120			37
Employer contributions		70			50			—
Benefits paid		(30	)		(1,257	)		—

Fair value of plan assets at end of year		1,639			552			589

Funded status recognized as an other (liability) asset		(164	)		308			570

Amounts recognized in accumulated other comprehensive income consist of the following:


	Year Ended December 31
	2021		2022		2023
	US$		US$		US$
Net loss		718		1,322		1,070

Total recognized in accumulated other comprehensive income		718		1,322		1,070

The accumulated benefit obligation for all defined benefit pension plans was US$1,085 thousand and US$162 thousand as of December 31, 2021 and 2022, respectively. The accumulated benefit obligation is approximately equal to the projected benefit obligation as of December 31, 2023.

The components of net periodic benefit cost are as follows:


	Year Ended December 31
	2021			2022			2023
	US$			US$			US$
Service cost		35			13			19
Interest cost		20			14			8
Projected return o n p lan assets		(33	)		(30	)		(17	)
Amortization of unrecognized net transition obligation and unrecognized net actuarial gain		34			35			24
Curtailment or settlement loss		—			156			—

Net periodic benefit cost		56			188			34

Other changes in plan assets and benefit obligation recognized in other comprehensive loss (income):


	2021			2022		2023
	US$			US$		US$
Recognize the decrease in net gain (loss)		(36	)		604		(252	)

Total recognized in other comprehensive loss (income)		(36	)		604		(252	)

Expected benefit payments:


	US$
2024		17
2025		5
2026		5
2027		5
2028		5
2029 and thereafter		101

The actuarial assumptions to determine the benefit obligations are as follows:


	2021			2022			2023
Weighted-average assumptions used to determine benefit obligations:
Discount rate		0.75	%		1.75	%		1.41	%
Rate of compensation increase		4.00	%		4.50	%		4.00	%
Weighted-average assumptions used to determine net projected benefit cost:
Discount rate		0.75	%		1.75	%		1.41	%
Expected long-term return on plan assets		2.00	%		3.00	%		3.00	%
Rate of compensation increase		4.00	%		4.50	%		4.00	%

- Definition

The entire disclosure for retirement benefits.

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+ Details

Expected Benefit Payments (Detail) $ in Thousands	Dec. 31, 2023 USD ($)
Retirement Benefits [Abstract]
2024	$ 17
2025	5
2026	5
2027	5
2028	5
2029 and thereafter	$ 101

Short-Term Bank Loans - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Short-term Debt [Line Items]
Proceeds from bank loan	$ 0	$ 40,000	$ 0
Interest expense	$ 0	$ 71	$ 0
Interest rate		4.55%

Changes in Benefits Obligation and Plan Assets and Reconciliation of Funded Status (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Change in benefit obligation
Projected benefit obligation at beginning of year	$ 244	$ 1,803	$ 1,716
Service cost	19	13	35
Interest cost	8	14	20
Actuarial loss (gain)	(252)	(205)	142
Benefits paid	0	(1,236)	(110)
Settlement	0	(145)	0
Projected benefit obligation at end of year	19	244	1,803
Change in plan assets
Fair value of plan assets at beginning of year	552	1,639	1,551
Actual return on plan assets	37	120	48
Employer contributions	0	50	70
Benefits paid	0	(1,257)	(30)
Fair value of plan assets at end of year	589	552	1,639
Funded status recognized as an other (liability) asset	$ 570	$ 308	$ (164)

Income (loss) Before Income Taxes for Domestic and Foreign Entities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Cayman	$ (17,082)	$ (39,449)	$ (22,847)
Non-Cayman	78,130	252,027	270,111
Income before taxes	$ 61,048	$ 212,578	$ 247,264

- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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+ Details

Cash, Cash Equivalents, and Restricted Cash (Tables)

12 Months Ended

Dec. 31, 2023

Cash and Cash Equivalents [Abstract]

Details of Cash, Cash Equivalents, and Restricted Cash


	December 31
	2022		2023
	US$		US$
Cash and deposits in bank		70,787		46,479
Time deposits		143,267		235,570
Repurchase agreements		18,125		32,253

Total cash and cash equivalents		232,179		314,302
Restricted cash		54,876		54,688

		287,055		368,990

Amounts Recognized in Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Retirement Benefits [Abstract]
Net loss	$ 1,070	$ 1,322	$ 718
Total recognized in accumulated other comprehensive income	$ 1,070	$ 1,322	$ 718	$ 754

Accrued Expenses and Other Current Liabilities (Tables)

12 Months Ended

Dec. 31, 2023

Payables and Accruals [Abstract]

Accrued Expenses and Other Current Liabilities


	December 31
	2022		2023
	US$		US$
Wages and bonus		53,987		37,881
Dividends		691		50,838
License fees and royalties		7,145		9,922
Research and development payable		9,355		15,953
Fixture		1,683		2,228
Lease liabilities – current portion		3,204		2,343
Equipment		2,311		1,523
Professional fees		3,986		8,380
Contract liabilities		6,909		6,438
Others		9,989		10,845

	99,260		146,351

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

Property and Equipment


	December 31
	2022		2023
	US$		US$
Cost:
Land		68,243		67,640
Buildings		29,314		28,668
Machinery and equipment		56,995		61,997
Furniture and fixtures		8,737		9,104
Leasehold and buildings improvement		9,057		8,360
Software		45,333		56,241

Total		217,679		232,010

Accumulated depreciation:
Buildings		6,356		6,544
Machinery and equipment		36,283		41,906
Furniture and fixtures		6,333		6,532
Leasehold and buildings improvement		7,689		6,029
Software		41,503		51,643

		98,164		112,654
Prepayment and construction in progress		19,919		48,061

		139,434		167,417

Segment Information (Tables)

12 Months Ended

Dec. 31, 2023

Segment Reporting [Abstract]

Revenue by Product Category

The Company groups its products into two categories, based on the markets in which they may be used. The following summarizes the Company’s revenue by product category:


	Year Ended December 31
	2021		2022		2023
	US$		US$		US$
Mobile Storage		910,569		926,760		632,813
Others		11,531		19,161		6,329

		922,100		945,921		639,142

Revenue by Geographic Area

Revenue is attributed to a geographic area based on the

bill-to

location and is summarized as follows:


	Year Ended December 31
	2021		2022		2023
	US$		US$		US$
Taiwan		159,575		156,205		74,284
United States		53,517		128,844		55,504
Korea		21,569		113,757		48,633
China		286,605		248,301		229,037
Malaysia		73,264		26,375		1,736
Singapore		219,214		141,383		127,642
Others		108,356		131,056		102,306

	922,100		945,921		639,142

Major customers representing at least 10% of net sales

Major customers representing at least 10% of net sales are as follows:


	Year Ended December 31
	2021				2022				2023
	US$		%		US$		%		US$		%
Intel		94,781		10		*		*		*		*
Micron		243,204		26		235,934		25		144,011		22
SK Hynix		*		*		191,873		20		75,836		12
AFASTOR		*		*		*		*		70,046		11

*	Less than 10 %

Long-Lived Assets (Property and Equipment, Net) by Geographic Area

Long-lived assets (property and equipment, net) by geographic area are as follows:


	Year Ended December 31
	2021		2022		2023
	US$		US$		US$
Taiwan		111,341		127,733		155,334
China		12,518		11,028		11,118
Others		619		673		965

		124,478		139,434		167,417

Accrued Expenses and Other Current Liabilities

12 Months Ended

Dec. 31, 2023

Payables and Accruals [Abstract]

Accrued Expenses and Other Current Liabilities

10. ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES


	December 31
	2022		2023
	US$		US$
Wages and bonus		53,987		37,881
Dividends		691		50,838
License fees and royalties		7,145		9,922
Research and development payable		9,355		15,953
Fixture		1,683		2,228
Lease liabilities – current portion		3,204		2,343
Equipment		2,311		1,523
Professional fees		3,986		8,380
Contract liabilities		6,909		6,438
Others		9,989		10,845

	99,260		146,351

Components of Income Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Current	$ 7,747	$ 42,594	$ 49,005
Deferred	428	(2,526)	(1,743)
Income tax expense	$ 8,175	$ 40,068	$ 47,262
Effective tax rate	13.40%	18.80%	19.10%

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

Table of Stock-based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	$ 17,547	$ 26,661	$ 19,545
Cost of Sales
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	406	597	389
Research and Development Expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	11,709	18,678	12,864
Selling and Marketing Expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	1,858	2,736	2,366
General and Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	$ 3,574	$ 4,650	$ 3,926

Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
NET SALES	$ 639,142	$ 945,921	$ 922,100
COST OF SALES	368,752	480,090	461,305
GROSS PROFIT	270,390	465,831	460,795
OPERATING EXPENSES
Research and development	174,357	188,532	164,291
Sales and marketing	26,920	31,537	28,813
General and administrative	27,923	31,447	21,822
Loss from settlement of litigation	1,312	390	0
Total operating expenses	230,512	251,906	214,926
OPERATING INCOME	39,878	213,925	245,869
NON-OPERATING INCOME (EXPENSES)
Unrealized holding gain on investment	8,002	896	0
Interest income	12,246	2,707	1,279
Foreign exchange gain (loss), net	914	(4,880)	193
Interest expense	0	(71)	0
Other income (loss), net	8	1	(77)
Total non-operating income (loss)	21,170	(1,347)	1,395
INCOME BEFORE INCOME TAX	61,048	212,578	247,264
INCOME TAX EXPENSE	8,175	40,068	47,262
NET INCOME	$ 52,873	$ 172,510	$ 200,002
EARNINGS PER ORDINARY SHARE:
Basic	$ 0.4	$ 1.3	$ 1.43
Diluted	$ 0.4	$ 1.29	$ 1.43
WEIGHTED AVERAGE ORDINARY SHARES OUTSTANDING
Basic (Thousands)	133,413	133,027	139,405
Diluted (Thousands)	133,879	133,553	139,968
EARNINGS PER ADS (one ADS equals four ordinary shares):
Basic	$ 1.59	$ 5.19	$ 5.74
Diluted	$ 1.58	$ 5.17	$ 5.72
WEIGHTED AVERAGE ADS OUTSTANDING
Basic (Thousands)	33,353	33,257	34,851
Diluted (Thousands)	33,470	33,388	34,992

Organization and Operations - Additional Information (Detail) - USD ($)			12 Months Ended
	Jul. 26, 2023	May 05, 2022	Dec. 31, 2023	Dec. 31, 2022
Organization and Operations [Line Items]
Common stock, par or stated value per share			$ 0.01	$ 0.01
Merger Agreement [Member] \| Maxlinear Inc [Member]
Organization and Operations [Line Items]
Payment for termination fee	$ 160,000,000
Merger Agreement [Member] \| Maxlinear Inc [Member] \| American Depositary Shares [Member]
Organization and Operations [Line Items]
Payments to Acquire Businesses, Gross			$ 93.54
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares			0.388
Merger Agreement [Member] \| Maxlinear Inc [Member] \| Common Stock [Member]
Organization and Operations [Line Items]
Payments to Acquire Businesses, Gross		$ 23.385
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares		0.097
Common stock, par or stated value per share		$ 0.0001

Property and Equipment (Detail) - USD ($) $ in Thousands	12 Months Ended
Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Land	$ 67,640	$ 68,243
Buildings	28,668	29,314
Machinery and equipment	61,997	56,995
Furniture and fixtures	9,104	8,737
Leasehold and buildings improvement	8,360	9,057
Software	56,241	45,333
Total	232,010	217,679
Accumulated Depreciation	112,654	98,164
Prepayment and construction in progress	48,061	19,919
Property, Plant and Equipment, Net	167,417	139,434	$ 124,478
Software
Property, Plant and Equipment [Line Items]
Accumulated Depreciation	51,643	41,503
Buildings
Property, Plant and Equipment [Line Items]
Accumulated Depreciation	6,544	6,356
Machinery and Equipment
Property, Plant and Equipment [Line Items]
Accumulated Depreciation	41,906	36,283
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Accumulated Depreciation	6,532	6,333
Leasehold and buildings improvement
Property, Plant and Equipment [Line Items]
Accumulated Depreciation	$ 6,029	$ 7,689

Property and Equipment

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

Property and Equipment

7. PROPERTY AND EQUIPMENT


	December 31
	2022		2023
	US$		US$
Cost:
Land		68,243		67,640
Buildings		29,314		28,668
Machinery and equipment		56,995		61,997
Furniture and fixtures		8,737		9,104
Leasehold and buildings improvement		9,057		8,360
Software		45,333		56,241

Total		217,679		232,010

Accumulated depreciation:
Buildings		6,356		6,544
Machinery and equipment		36,283		41,906
Furniture and fixtures		6,333		6,532
Leasehold and buildings improvement		7,689		6,029
Software		41,503		51,643

		98,164		112,654
Prepayment and construction in progress		19,919		48,061

		139,434		167,417

In April 2006, the Company leased a property located in Taipei, Taiwan to a third party. The lessee had been renewing annually and last renewed in March 2023. The rental income from the lease in 2021, 2022 and 2023 were US$44 thousand, US$44 thousand and US$36 thousand, respectively. Net carrying value of

the pr

operty as of December 31, 2022 was US$617 thousand. In October 2023, the company terminated the lease contract and subsequently sold the property to the lessee, resulting in a disposal gain of US$594 thousand.

In January 2022, the Company leased out parts of property located in Shanghai, China to a third party for three years starting on September 30, 2022. In December 2023, the Company leased out part of property located in Shanghai, China to another third party for three years starting on February 1, 2024. Net carrying value of the property as of December 31, 2022 and 2023, was US$3,284 thousand and US$3,154 thousand, respectively. The rental income from the lease in 2022 and 2023 were US$157 thousand and US$151 thousand, respectively.

In September 2018, the Company paid US$58,931 thousand to acquire land in Hsinchu, Taiwan for its future Taiwan headquarter building. In January 2021, the Company broke ground at this site and began construction work.

Shareholders' Equity (Tables)

12 Months Ended

Dec. 31, 2023

Federal Home Loan Banks [Abstract]

Cash Dividends Declared Per Ordinary Share

The Company’s quarterly dividends payments are as follows:


	2021				2022				2023
	Dividends Per Share (US$)		Amount (in US$ thousand)		Dividends Per Share (US$)		Amount (in US$ thousand)		Dividends Per Share (US$)		Amount (in US$ thousand)
First quarter	$	0.0875	$	12,222	$	0.1250	$	17,216	$	—	$	—
Second quarter		0.0875		12,224		0.1250		16,523		—		—
Third quarter		0.0875		12,227		0.1250		16,526		—		—
Fourth quarter		0.1250		17,469		—		—		0.1250		16,708

			$	54,142			$	50,265			$	16,708

Consolidated Statements Of Changes In Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended												12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2023	Dec. 31, 2021
Statement of Stockholders' Equity [Abstract]
Dividends declared, per share	$ 0.125	$ 0	$ 0	$ 0	$ 0	$ 0.125	$ 0.125	$ 0.125	$ 0.125	$ 0.0875	$ 0.0875	$ 0.0875	$ 0.5	$ 0.5

Change In Allowances (Detail) - USD ($) $ in Thousands	12 Months Ended
Change In Allowances (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Allowances for doubtful accounts
Balance, beginning of year	$ 569	$ 540	$ 1,561
Additions (reversals) charged to expense, net	(549)	29	(21)
Write-offs	0	0	(1,000)
Balance, end of year	$ 20	$ 569	$ 540

Equity Incentive Plan

12 Months Ended

Dec. 31, 2023

Share-based Payment Arrangement [Abstract]

Equity Incentive Plan

14. EQUITY INCENTIVE PLAN

2015 Equity

Incentive

Plan

Restricted stock units are converted into shares of the Company’s ordinary shares upon vesting

one-for-one

basis. The vesting of restricted stock unit is subject to the employee’s continuing service to the Company. The cost of these awards is determined using the fair value of the Company’s ordinary share on the date of the grant, and compensation is recognized on a straight-line basis over the requisite service period. The Company’s restricted stock units are

considered non-vested

share awards as defined under ASC 718.

On June 3, 2015, the Company adopted its 2015 Equity Incentive Plan (“the 2015 Plan”). The 2015 Plan provides for the grant of stock options, stock bonuses, restricted stock awards, restricted stock units and stock appreciation rights, which may be granted to employees (including officers), directors and consultants. The 2015 Plan reserved 20,000 thousand shares of ordinary shares for issuance upon exercise of stock options and restricted stock units.

Restricted Stock Units Activity

The following is a summary of, the 2015 Plan, which includes restricted stock units:


	Unit (in Thousands)
Available for grant at January 1, 2021		12,625
Restricted stock units granted		(2,326	)
Restricted stock units forfeited		134

Available for grant at December 31, 2021		10,433
Restricted stock units granted		(902	)
Restricted stock units forfeited		49

Available for grant at December 31, 2022		9,580
Restricted stock units granted		(624	)
Restricted stock units forfeited		51

Available for grant at December 31, 2023		9,007

The related tax effect for stock-based compensation benefit (expense) were US$(155) thousand, US$2 thousand and US$(178) thousand for 2021, 2022 and 2023, respectively. The related tax effect for stock-based compensation expense for restricted stock units exercised during 2021, 2022 and 2023 was US$2,767 thousand, US$3,957 thousand and US$4,925 thousand, respectively. The related tax effect was determined using applicable tax rates.

Restricted Stock Units

A summary of the status of restricted stock units and changes is as follows:


	Number of Non-vested Stock Units (in Thousands)			Weighted Average Grant Date Fair Value (US$)		Weight Average Remaining Recognition Period (Years)
Non-vested at January 1, 2021		1,714			9.37		0.31
Restricted stock units granted		2,326			17.62
Restricted stock units vested		(1,596	)		9.31
Restricted stock units forfeited		(134	)		14.99

Non-vested at December 31, 2021		2,310			17.37		1.57
Restricted stock units granted		902			19.56
Restricted stock units vested		(1,186	)		17.61
Restricted stock units forfeited		(49	)		17.18

Non-vested at December 31, 2022		1,977			17.89		0.66
Restricted stock units granted		624			13.51
Restricted stock units vested		(1,460	)		18.36
Restricted stock units forfeited		(51	)		16.38

Non-vested at December 31, 2023		1,090			15.00		0.13

As of December 31, 2023, there was US$2,076 thousand of total unrecognized compensation cost related to restricted stock units granted under the 2015 Plan.

Stock-based Compensation Expense

The following table shows total stock-based compensation expense included in the Consolidated Statements of Income for the years ended December 31, 2021, 2022 and 2023.


	Year Ended December 31
	2021		2022		2023
	US$		US$		US$
Cost of sales		389		597		406
Research and development		12,864		18,678		11,709
Sales and marketing		2,366		2,736		1,858
General and administrative		3,926		4,650		3,574

		19,545		26,661		17,547

Inventories (Tables)

12 Months Ended

Dec. 31, 2023

Inventory Disclosure [Abstract]

Components of Inventory

The components of inventories are as follows:


	December 31
	2022		2023
	US$		US$
Finished goods		98,307		61,336
Work in process		111,530		86,930
Raw materials		78,127		68,684

		287,964		216,950

Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Balance, beginning of year	$ 37,105	$ 26,317	$ 19,001
Increases in tax positions taken in current year	16,054	13,705	8,750
Decrease in tax position taken in prior year primarily related to the resolution of tax audit	(9,395)	(2,917)	(1,434)
Balance, end of year	$ 43,764	$ 37,105	$ 26,317

Major customers representing at least 10% of net sales (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenue, Major Customer [Line Items]
NET SALES	$ 639,142	$ 945,921	$ 922,100
Net sales \| Customers accounted for 10% or more \| Intel
Revenue, Major Customer [Line Items]
NET SALES			$ 94,781
Major customers, percentage of net sales			10.00%
Net sales \| Customers accounted for 10% or more \| Micron
Revenue, Major Customer [Line Items]
NET SALES	$ 144,011	$ 235,934	$ 243,204
Major customers, percentage of net sales	22.00%	25.00%	26.00%
Net sales \| Customers accounted for 10% or more \| SK Hynix
Revenue, Major Customer [Line Items]
NET SALES	$ 75,836	$ 191,873
Major customers, percentage of net sales	12.00%	20.00%
Net sales \| Customers accounted for 10% or more \| AFASTOR
Revenue, Major Customer [Line Items]
NET SALES	$ 70,046
Major customers, percentage of net sales	11.00%

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 924
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479941/924-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-5

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 30
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-30

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-42

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
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-Paragraph 32
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-40

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 41
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-41

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-4

+ Details

Income Taxes

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Income Taxes

12. INCOME TAXES

Income Tax Provision

The income (loss) before taxes for Cayman and

Non-Cayman

entities is as follows:


	Year Ended December 31
	2021			2022			2023
	US$			US$			US$
Cayman		(22,847	)		(39,449	)		(17,082	)
Non-Cayman		270,111			252,027			78,130

Income before taxes		247,264			212,578			61,048

The components of income tax provision (benefit) were as follows:


	Year Ended December 31
	2021			2022			2023
	US$			US$			US$
Current		49,005			42,594			7,747
Deferred		(1,743	)		(2,526	)		428

Income tax expense		47,262			40,068			8,175


Effective tax rate		19.1	%		18.8	%		13.4	%

The Company’s business operations are primarily located in China, Hong Kong, Macau, Taiwan and the US, where statutory and effective tax rates in each jurisdiction are different, and our consolidated effective tax rate could change from

period-to-period

due to changing statutory tax rates, availability of tax benefits and proportional income earned in each jurisdiction. The statutory tax rates in these jurisdictions range from 12 to 21%. For the year ended December 2023, the Company’s effective tax rate was 13.4%, lower than 19.1% and 18.8% in 2021 and 2022 due to changes in proportional income earned by operations in key jurisdictions. Effective tax rates in each jurisdiction are generally lower than statutory rates due to tax credits for research and development and other tax incentive programs and are determined by different government policies in each of the jurisdictions where the Company operates.

The Company consists of a Cayman parent holding company with U.S. and other

non-Cayman

operations. The applicable Cayman statutory rate is zero for the Company for 2021, 2022, and 2023. A reconciliation of its income tax expense at the statutory rate and provision for income tax is shown below:


	Year Ended December 31
	2021			2022			2023
	US$			US$			US$
Tax expense at Cayman statutory rate		—			—			—
Differences between Cayman and other statutory tax rates		48,322			38,696			9,979
Permanent differences		(10,625	)		(3,377	)		206
Temporary differences		(400	)		(1,091	)		(1,614	)
Alternative minimum tax		1			1			1
Income tax on undistributed earnings		3,609			1,874			—
Net changes in income tax credit		1,261			(38	)		(205	)
Net changes in valuation allowance of deferred income tax assets		1,066			(302	)		3,260
Net operating loss carryforwards		180			1,668			(1,805	)
Liabilities related to unrealized tax benefits		5,877			11,036			5,482
Adjustment of prior years’ taxes and others		(2,029	)		(8,399	)		(7,129	)

Income tax expense		47,262			40,068			8,175

Deferred and Current Income Taxes

Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts for income tax purposes.

Significant components of our deferred tax assets (liabilities) at the end of each period are as follows:


	December 31
	2022			2023
	US$			US$
Stock-based compensation		3,058			1,430
Allowance for sales return		1,000			392
Inventory reserve		2,428			2,983
Foreign currency translation		(48	)		(35	)
Property and equipment		(576	)		(1,076	)
Investment tax credits		3,290			3,495
Net operating loss carryforwards		18,057			21,332
Others		1,838			3,055
Valuation allowance		(20,163	)		(23,120	)

Net deferred tax assets		8,884			8,456

The valuation allowance shown in the table above relates to net operating loss carryforwards, tax credits and temporary differences for which the Company believes that realization is uncertain. Valuation allowance decreased by US$1,644 thousand for the year ended December 31, 2022 and increased by US$2,957 thousand for the year ended December 31, 2023, respectively. The decrease in valuation allowance in 2022 was primarily a result of a reduction in operating losses and tax credits, offset partially by the capitalized research expenditures. The increase in valuation allowance in 2023 had been based on all available evidence, particularly the earnings history and forecasts of future taxable income in each respective jurisdiction.

As of December 31, 2023, the Company’s U.S. federal net operating loss carryforwards for federal income tax purposes were approximately US$23,605 thousand as of December 31, 2023, expiring at various times starting from 2024 through 2037 for federal losses generated through December 31, 2017, if not utilized. As a result of the U.S. Tax Cuts and Jobs Act (TCJA), all federal net operating losses of US$17,193 thousand that are generated beginning January 1, 2018 and beyond will carryforward indefinitely.

As of December 31, 2023, the Company’s U.S. federal and state research and development tax credit carryforwards for federal and state income tax purposes were approximately US$2,132 thousand and US$1,363 thousand, respectively. If not utilized, the federal tax credit carryforwards will expire starting in 2043, while the state tax credit carryforward has no expiration date in California.

Current U.S. federal and California state laws include substantial restrictions on the utilization of net operating losses and credits in the event of an “ownership change” of a corporation. Accordingly, the Company’s ability to utilize net operating loss and tax credit carryforwards may be limited as a result of such “ownership change”. Such a limitation could result in the expiration of carryforwards before they are utilized.

As of December 31, 2023, the Company had accumulated undistributed earnings from a foreign subsidiary of US$487 million. No deferred tax liability was recorded in respect of those amounts as these earnings are considered indefinitely reinvested. It is not practicable to estimate the amount of unrecognized deferred tax liabilities for these undistributed foreign earnings.

Unrecognized Tax Benefit

A reconciliation of the beginning and ending balances of the total amounts of unrecognized tax benefits is as follows:


	Year Ended December 31
	2021			2022			2023
	US$			US$			US$
Balance, beginning of year		19,001			26,317			37,105
Increases in tax positions taken in current year		8,750			13,705			16,054
Decrease in tax position taken in prior year primarily related to the resolution of tax audit		(1,434	)		(2,917	)		(9,395	)

Balance, end of year		26,317			37,105			43,764

At December 31, 2023, the Company had US$43,764 thousand of unrecognized tax benefits that if recognized would affect the effective tax rate. For the years ended December 31, 2021, 2022 and 2023, the total amount of interest expense and penalties related to uncertain tax positions recorded in the provision for income tax expense was approximately US$1,040 thousand, US$1,037 thousand and US$1,072 thousand, respectively. The total amount of accrued interest and penalties recognized as of December 31, 2022 and 2023 was US$6,777 thousand and US$7,850 thousand, respectively. The Company does not expect uncertain tax positions to change in the next twelve months, except in the case of settlements with tax authorities, the likelihood and timing of which are difficult to estimate.

The Company files income tax returns in the U.S. and foreign jurisdictions. The following table summarizes the Company’s major jurisdictions and tax year that remain subject to examination by tax authorities as of December 31, 2023:


Tax Jurisdiction		Tax Years
China		2020 and onward
Hong Kong		2020 and onward
Taiwan		2018 and onward
United States		2018 onward

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
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-Section S99
-Paragraph 1
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-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-Name Accounting Standards Codification
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-URI https://asc.fasb.org//740/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-14

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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-URI https://asc.fasb.org//1943274/2147482685/740-10-50-21

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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-Subparagraph (b)
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482603/740-30-50-2

+ Details

Organization and Operations	12 Months Ended
Organization and Operations	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Operations	1. ORGANIZATION AND OPERATIONS Silicon Motion Technology Corporation (“SMTC”, collectively with its subsidiaries the “Company”) is the global leader in supplying NAND flash controllers for solid state storage devices. The Company is a world leading supplier of SSD controllers for servers, PCs and other client devices and is a leading merchant supplier of eMMC and UFS embedded storage controllers used in smartphones, IoT devices and other applications. The Company also supplies customized high-performance and specialized industrial and automotive SSD solutions. Our customers include most of the NAND flash vendors, storage device module makers and leading OEMs. For further information on Silicon Motion, visit us at www.siliconmotion.com. Termination of the Merger Agreement with MaxLinear On May 5, 2022, the Company entered into an Agreement and Plan of Merger (the “Merger Agreement”) with MaxLinear, Inc., a Delaware Corporation (“MaxLinear”), and Shark Merger Sub, an exempted company with limited liability incorporated under the law of the Cayman Islands and a wholly owned subsidiary of MaxLinear, pursuant to which the Company agreed to be acquired by MaxLinear, with (a) holders of our ordinary shares to receive $23.385 in cash and 0.097 shares of MaxLinear common stock, par value $0.0001(“MaxLinear Common Stock”) for each share that they hold (other than certain customary excluded shares), and (b) ADS holders to receive $93.54 in cash and 0.388 shares of MaxLinear Common Stock for each ADS that they hold (other than ADSs representing certain customary excluded shares), in each case, with cash in lieu of any fractional shares of MaxLinear Common Stock (collectively, the “Transaction”). On August 31, 2022, shareholders at the Company’s Extraordinary General Meeting of Shareholders approved the Transaction. On July 26, 2023, the Company and MaxLinear received antitrust approval from the State Administration for Market Regulation of the People’s Republic of China (“SAMR Approval”). Shortly after receiving SAMR Approval, the Company received notice from MaxLinear of its purported termination of the Merger Agreement. MaxLinear did not provide any factual basis for its purported termination, and the Company believes its actions constituted a willful and material breach of the Merger Agreement. The Company has filed a claim in the Singapore International Arbitration Centre (the “SIAC”), which is the venue for dispute resolution under the Merger Agreement, and is currently pursuing payment of the termination fee of $160 million, together with further substantial damages, interest and costs. Under the SIAC Arbitration Rules, all matters relating to the proceedings are confidential.

Long-lived Assets (Property And Equipment, net) by Geographic Area (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	$ 167,417	$ 139,434	$ 124,478
Taiwan
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	155,334	127,733	111,341
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	11,118	11,028	12,518
Others
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	$ 965	$ 673	$ 619

Short-Term Bank Loans	12 Months Ended
Short-Term Bank Loans	Dec. 31, 2023
Debt Disclosure [Abstract]
Short-Term Bank Loans	8. SHORT-TERM BANK LOANS The Company has a US dollar bank revolver credit facility from which it drew down and repaid US$$40,000 thousand in 2022. Interest rate was 4.55% per annum on the outstanding monthly balance in 2022. The interest expenses for the years ended December 31, 2021, 2022 and 2023 were nil, US$71 thousand and nil, respectively.

Lease

12 Months Ended

Dec. 31, 2023

Leases [Abstract]

Lease

15. LEASE

Operating Leases

The Company entered into various operating lease agreements, which consist of real property and office equipment with lease periods expiring between fiscal years 2023 and 2033. The Company recognized leased assets in operating lease assets of US$8,149 and US$14,134 thousand and corresponding accrued expenses and other current liabilities of US$3,204 and US$2,343 thousand, and

other long-term

liabilities

of US$4,908 and US$12,696 thousand, as of December 31, 2022 and 2023, respectively. The weighted average remaining lease term was 3.14 years and 8.07 years, and the weighted average discount rate was 2.38% and 2.56% as of December 31, 2022 and 2023, respectively.

The aggregate future lease payments for the operating leases under the operating leases as of December 31, 2023, were as follows:


	Operating Lease Obligations
Fiscal Year:
2024	$	2,687
2025		2,329
2026		2,010
2027		1,522
2028		1,303
2029 and thereafter		6,688

Total		16,539
Less imputed interest		1,500

Present value of lease liabilities		15,039
Less operating lease liabilities-current		2,343

Long-term operating lease liabilities	$	12,696

Operating lease expenses for the years ended December 31, 2021, 2022 and 2023 are US$4,574 thousand, US$4,820 thousand, and US$5,261 thousand, respectively. For the supplemental cash flow information related to lease, the cash paid for amounts included in the measurement of operating lease liabilities was US$3,502 thousand, US$3,642 thousand and US$3,825 thousand for the year ended December 31, 2021, 2022 and 2023, respectively.

Refund Liabilities - Summary of Change in Refund Liabilities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Other Liabilities [Abstract]
Balance, beginning of year	$ 6,471	$ 3,882
Additions	5,780	19,196
Actual sales return and discount	(8,922)	(16,607)
Balance, end of year	$ 3,329	$ 6,471

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Tax Credit Carryforward [Line Items]
Change in valuation allowance	$ 2,957	$ (1,644)
Accumulated undistributed earnings from a foreign subsidiary	487,000
Deferred tax liability on undistributed foreign earnings	0
Unrecognized tax benefit	43,764	37,105	$ 26,317	$ 19,001
Total amount of interest expense and penalties	1,072	1,037	$ 1,040
Total amount of accrued interest and penalties	$ 7,850	$ 6,777
Effective Income Tax Rate Reconciliation, Percent	13.40%	18.80%	19.10%
Minimum
Tax Credit Carryforward [Line Items]
Corporate income tax rate	12.00%
Maximum
Tax Credit Carryforward [Line Items]
Corporate income tax rate	21.00%
Foreign Tax Authority \| Internal Revenue Service (IRS) [Member] \| Tax Year 2017 [Member]
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards for income tax purposes	$ 23,605
Foreign Tax Authority \| Internal Revenue Service (IRS) [Member] \| Tax Year 2018 [Member]
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards for income tax purposes	$ 17,193
Operating loss carryforward expiration year description	carryforward indefinitely.
Foreign Tax Authority \| Maximum \| Internal Revenue Service (IRS) [Member] \| Tax Year 2017 [Member]
Tax Credit Carryforward [Line Items]
Federal net operating loss carryforwards expiration year	2037
Foreign Tax Authority \| Research And Development \| Internal Revenue Service (IRS) [Member]
Tax Credit Carryforward [Line Items]
Deferred tax assets tax credit carryforwards	$ 2,132
Tax credit carryforward expiration year for federal	2043
State and Local Jurisdiction [Member] \| Minimum \| Internal Revenue Service (IRS) [Member] \| Tax Year 2017 [Member]
Tax Credit Carryforward [Line Items]
Federal net operating loss carryforwards expiration year	2024
State and Local Jurisdiction [Member] \| Research And Development
Tax Credit Carryforward [Line Items]
Deferred tax assets tax credit carryforwards	$ 1,363
Tax credit carryforward expiration year for state	no expiration date in California

Lease - Summary of Future Lease Payments for the Operating Leases Under the Operating Leases (Detail) $ in Thousands	Dec. 31, 2023 USD ($)
Leases [Abstract]
2024	$ 2,687
2025	2,329
2026	2,010
2027	1,522
2028	1,303
2029 and thereafter	6,688
Total	16,539
Less imputed interest	1,500
Present value of lease liabilities	15,039
Less operating lease liabilities-current	2,343
Long-term operating lease liabilities	$ 12,696
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Liabilities, Current
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other Liabilities, Noncurrent

Accounts Receivable

12 Months Ended

Dec. 31, 2023

Receivables [Abstract]

Accounts Receivable

. ACCOUNTS RECEIVABLE


	December 31
	2022			2023
	US$			US$
Trade accounts receivable		206,674			194,721
Allowance for doubtful accounts		(569	)		(20	)

		206,105			194,701

The changes in the allowances are summarized as follows:


	Year Ended December 31
	2021			2022		2023
	US$			US$		US$
Allowances for doubtful accounts
Balance, beginning of year		1,561			540		569
Additions (reversals) charged to expense, net		(21	)		29		(549	)
Write-offs		(1,000	)		—		—

Balance, end of year		540			569		20

Components of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Assets and Liabilities Eliminated upon Consolidation [Abstract]
Beginning balance, Foreign currency items	$ 3,917	$ 178	$ 405
Current-period change, Foreign currency items	(1,694)	3,739	(227)
Ending balance, Foreign currency items	2,223	3,917	178
Beginning balance, Defined benefit pension plans	(1,322)	(718)	(754)
Current-period change, Defined benefit pension plans	252	(604)	36
Ending balance, Defined benefit pension plans	(1,070)	(1,322)	(718)
Beginning balance, Accumulated other comprehensive income (loss)	2,595	(540)	(349)
Current-period change, Accumulated other comprehensive income (loss)	(1,442)	3,135	(191)
Ending balance, Accumulated other comprehensive income (loss)	$ 1,153	$ 2,595	$ (540)

- Definition

Amount, after tax, of accumulated increase (decrease) in equity from transaction and other event and circumstance from nonowner source.

+ References + Details

- Definition

Amount after tax and reclassification adjustments of other comprehensive income (loss).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
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Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
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-Name Accounting Standards Codification
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Paragraph 20
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
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-Name Accounting Standards Codification
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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-Section 45
-Paragraph 1A
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482790/220-10-45-1A

+ Details

Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Wages and bonus	$ 37,881	$ 53,987
Dividends	50,838	691
License fees and royalties	9,922	7,145
Research and development payable	15,953	9,355
Fixture	2,228	1,683
Lease liabilities – current portion	2,343	3,204
Equipment	1,523	2,311
Professional fees	8,380	3,986
Contract liabilities	6,438	6,909
Others	10,845	9,989
Accrued expenses and other current liabilities	$ 146,351	$ 99,260

Reconciliation of Income Tax Expense on Pretax Income at Statutory Rate and Income Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reconciliation Of Income Taxes [Line Items]
Differences between Cayman and foreign statutory tax rates	$ 9,979	$ 38,696	$ 48,322
Permanent differences	206	(3,377)	(10,625)
Temporary differences	(1,614)	(1,091)	(400)
Alternative minimum tax	1	1	1
Income tax on undistributed earnings	0	1,874	3,609
Net changes in income tax credit	(205)	(38)	1,261
Net changes in valuation allowance of deferred income tax assets	3,260	(302)	1,066
Net operating loss carryforwards	(1,805)	1,668	180
Liabilities related to unrealized tax benefits	5,482	11,036	5,877
Adjustment of prior years' taxes and others	(7,129)	(8,399)	(2,029)
Income tax expense	8,175	40,068	47,262
Cayman Islands Tax Information Authority [Member]
Reconciliation Of Income Taxes [Line Items]
Tax expense at statutory rate

Revenue by Geographic Area (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenues from External Customers and Long-Lived Assets [Line Items]
NET SALES	$ 639,142	$ 945,921	$ 922,100
Taiwan
Revenues from External Customers and Long-Lived Assets [Line Items]
NET SALES	74,284	156,205	159,575
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
NET SALES	55,504	128,844	53,517
Korea
Revenues from External Customers and Long-Lived Assets [Line Items]
NET SALES	48,633	113,757	21,569
China
Revenues from External Customers and Long-Lived Assets [Line Items]
NET SALES	229,037	248,301	286,605
Malaysia
Revenues from External Customers and Long-Lived Assets [Line Items]
NET SALES	1,736	26,375	73,264
Singapore
Revenues from External Customers and Long-Lived Assets [Line Items]
NET SALES	127,642	141,383	219,214
Others
Revenues from External Customers and Long-Lived Assets [Line Items]
NET SALES	$ 102,306	$ 131,056	$ 108,356

- Definition

+ References

+ Details

Equity Incentive Plan (Tables)

12 Months Ended

Dec. 31, 2023

Share-based Payment Arrangement [Abstract]

Summary of Stock Option and Restricted Stock Units Activity

The following is a summary of, the 2015 Plan, which includes restricted stock units:


	Unit (in Thousands)
Available for grant at January 1, 2021		12,625
Restricted stock units granted		(2,326	)
Restricted stock units forfeited		134

Available for grant at December 31, 2021		10,433
Restricted stock units granted		(902	)
Restricted stock units forfeited		49

Available for grant at December 31, 2022		9,580
Restricted stock units granted		(624	)
Restricted stock units forfeited		51

Available for grant at December 31, 2023		9,007

Summary of Restricted Stock Units and Changes

A summary of the status of restricted stock units and changes is as follows:


	Number of Non-vested Stock Units (in Thousands)			Weighted Average Grant Date Fair Value (US$)		Weight Average Remaining Recognition Period (Years)
Non-vested at January 1, 2021		1,714			9.37		0.31
Restricted stock units granted		2,326			17.62
Restricted stock units vested		(1,596	)		9.31
Restricted stock units forfeited		(134	)		14.99

Non-vested at December 31, 2021		2,310			17.37		1.57
Restricted stock units granted		902			19.56
Restricted stock units vested		(1,186	)		17.61
Restricted stock units forfeited		(49	)		17.18

Non-vested at December 31, 2022		1,977			17.89		0.66
Restricted stock units granted		624			13.51
Restricted stock units vested		(1,460	)		18.36
Restricted stock units forfeited		(51	)		16.38

Non-vested at December 31, 2023		1,090			15.00		0.13

Stock-based Compensation Expense

The following table shows total stock-based compensation expense included in the Consolidated Statements of Income for the years ended December 31, 2021, 2022 and 2023.


	Year Ended December 31
	2021		2022		2023
	US$		US$		US$
Cost of sales		389		597		406
Research and development		12,864		18,678		11,709
Sales and marketing		2,366		2,736		1,858
General and administrative		3,926		4,650		3,574

		19,545		26,661		17,547

Summary of Accounts Receivable (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Receivables [Abstract]
Trade accounts receivable	$ 194,721	$ 206,674
Allowance for doubtful accounts	(20)	(569)	$ (540)	$ (1,561)
Accounts receivable, net	$ 194,701	$ 206,105

Accounts Receivable (Tables)

12 Months Ended

Dec. 31, 2023

Receivables [Abstract]

Summary of Accounts Receivable


	December 31
	2022			2023
	US$			US$
Trade accounts receivable		206,674			194,721
Allowance for doubtful accounts		(569	)		(20	)

		206,105			194,701

Changes in Allowances

The changes in the allowances are summarized as follows:


	Year Ended December 31
	2021			2022		2023
	US$			US$		US$
Allowances for doubtful accounts
Balance, beginning of year		1,561			540		569
Additions (reversals) charged to expense, net		(21	)		29		(549	)
Write-offs		(1,000	)		—		—

Balance, end of year		540			569		20

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	16. COMMITMENTS AND CONTINGENCIES Office Building Construction On February 18, 2021, the Company won a bid with a third-party to build an office building in Taipei and entered into a property development agreement in May 2021, at which time it delivered a US$5,322 thousand performance bond secured by a certificate of deposit. Based on the terms of the property development agreement, the Company is required to complete construction within three years after the construction license is approved. As of the date of this annual report, the government has yet to approve the construction license required for the project. Litigation On June 2, 2023, the Company was named as a defendant in a patent infringement lawsuit which was filed by Unification Technologies LLC in the United States District Court for the Eastern District of Texas, Marshall Divisions. After the Company filed an inter partes review petition to invalidate one of the asserted patents on December 18, 2023, the Company reached a mutually agreed settlement with Unification Technologies LLC., which provides for payment by the Company is not expected to a material adverse effect on our business, results of operations, financial position or cash flow. The terms and conditions of the settlement are confidential under this agreement and subject to a nondisclosure obligation. On August 10, 2023, a customer of the Company’s subsidiary, Bigtera (Beijing) Ltd., filed a lawsuit in Beijing Chaoyang District Court against Bigtera (Beijing) Ltd., asserting that Bigtera (Beijing) Ltd. is in breach of its two purchase contracts with the said customer due to ceasing its operation. Beijing Chaoyang District Court accepted this case, but no court date has been scheduled so far. The ultimate outcome cannot be reasonably estimated at the current stage. On October 5, 2023, we filed a claim in the SIAC against MaxLinear for breaching the Merger Agreement. In the arbitration, we are seeking payment of the termination fee of US$160 million, together with further substantial damages, interests, and costs. However, in the event that an award is handed down in favor of the Company there is a risk that it will not be able to collect the award due to MaxLinear’s financial condition. In addition, there is a risk that if the Company does not prevail on some or all of its claims, there is a risk that it can be required to pay some or all of MaxLinear’s legal fees and costs. The arbitration tribunal has been constituted, a procedural timetable has been issued and a hearing has been fixed for October 2025. Under the SIAC Arbitration Rules, all matters relating to the proceeding are confidential. On November 20, 2023, MaxLinear filed its defense to the aforementioned claims, asserting that the Company breached the Merger Agreement because its business allegedly sustained a material adverse effect and it failed to operate its business in the ordinary course. MaxLinear also asserted a claim for fraud, alleging that the projections that it was provided prior to entering into the Merger Agreement were inflated. MaxLinear seeks damages in an unspecified amount. The Company believes that the claims are meritless. The ultimate outcome cannot be reasonably estimated at the current stage.

Shareholders' Equity

12 Months Ended

Dec. 31, 2023

Federal Home Loan Banks [Abstract]

Shareholders' Equity

13. SHAREHOLDERS’ EQUITY

Dividends

The Company’s quarterly dividends payments are as follows:


	2021				2022				2023
	Dividends Per Share (US$)		Amount (in US$ thousand)		Dividends Per Share (US$)		Amount (in US$ thousand)		Dividends Per Share (US$)		Amount (in US$ thousand)
First quarter	$	0.0875	$	12,222	$	0.1250	$	17,216	$	—	$	—
Second quarter		0.0875		12,224		0.1250		16,523		—		—
Third quarter		0.0875		12,227		0.1250		16,526		—		—
Fourth quarter		0.1250		17,469		—		—		0.1250		16,708

			$	54,142			$	50,265			$	16,708

On November 2, 2015, the board of directors began declaring an annual dividend payable in four quarterly installments. The board of directors declared annual dividends of US$2.0 and US$2.0 per ADS, equivalent to US$0.5 and US$0.5 per common share, payable in four quarterly installments on October 25, 2021 and October 30, 2023, respectively. Future dividends, if any, will be declared by and subject to the discretion of the Company’s board of directors.

Share Repurchase

On November 21, 2018, the board of directors of the Company authorized the repurchase of up to US$200 million of the Company’s ADSs over a 24 month period. On October 26, 2020, the board of directors of the Company authorized the extension of the expiration of this program to November 21, 2021. On December 7, 2021, the board of directors of the Company authorized the repurchase of up to US$200 million of the Company’s ADSs over a 6 month period.

For the years ended December 31, 2021 and 2022, the Company repurchased

556 thousand and 1,627 thousand for a total cost of US$50,011 thousand and US$128,840 thousand, respectively. The weighted average purchase price per ADSs repurchased was US$89.87 and US$79.18 in 2021 and 2022, respectively.

- Definition

The entire disclosure for equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (d)
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-SubTopic 40
-Name Accounting Standards Codification
-Section 50
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-Subparagraph (a)
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
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-Topic 235
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-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//505/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Subparagraph (b)
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-Topic 505
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

+ Details

Actuarial Assumptions to Determine Benefit Obligations (Detail)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Weighted-average assumptions used to determine benefit obligations:
Discount rate	1.41%	1.75%	0.75%
Rate of compensation increase	4.00%	4.50%	4.00%
Weighted-average assumptions used to determine net projected benefit cost:
Discount rate	1.41%	1.75%	0.75%
Expected long-term return on plan assets	3.00%	3.00%	2.00%
Rate of compensation increase	4.00%	4.50%	4.00%

Inventories

12 Months Ended

Dec. 31, 2023

Inventory Disclosure [Abstract]

Inventories

5. INVENTORIES

The components of inventories are as follows:


	December 31
	2022		2023
	US$		US$
Finished goods		98,307		61,336
Work in process		111,530		86,930
Raw materials		78,127		68,684

		287,964		216,950

The Company wrote down US$5,689 thousand, US$15,833 thousand and US$7,920 thousand in 2021, 2022 and 2023, respectively, for obsolete or unmarketable inventory.

Summary of Stock Option and Restricted Stock Units Activity (Detail) - The 2005 Plan and The 2015 Plan - Employee Stock Options And Restricted Stock Units [Member] - shares shares in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Available for grant at beginning date	9,580	10,433	12,625
Restricted stock units granted	(624)	(902)	(2,326)
Restricted stock units forfeited	51	49	134
Available for grant at ending balance	9,007	9,580	10,433

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
-Section 35
-Paragraph 1D
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-URI https://asc.fasb.org//1943274/2147480483/718-10-35-1D

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (a)(2)
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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Reference 20: http://www.xbrl.org/2003/role/disclosureRef
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Reference 23: http://www.xbrl.org/2003/role/disclosureRef
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Reference 24: http://www.xbrl.org/2003/role/disclosureRef
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Reference 25: http://www.xbrl.org/2003/role/disclosureRef
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Reference 26: http://www.xbrl.org/2003/role/disclosureRef
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Reference 27: http://www.xbrl.org/2003/role/disclosureRef
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Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

+ Details

Deferred Income Tax Assets (liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Stock-based compensation	$ 1,430	$ 3,058
Allowance for sales return	392	1,000
Inventory reserve	2,983	2,428
Foreign currency translation	(35)	(48)
Property and equipment	(1,076)	(576)
Investment tax credits	3,495	3,290
Net operating loss carryforwards	21,332	18,057
Others	3,055	1,838
Valuation allowance	(23,120)	(20,163)
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent	$ 8,456	$ 8,884

Cash Dividends Declared Per Ordinary Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Dividends [Abstract]
Dividend Per Share	$ 0.125	$ 0	$ 0	$ 0	$ 0	$ 0.125	$ 0.125	$ 0.125	$ 0.125	$ 0.0875	$ 0.0875	$ 0.0875	$ 0.5		$ 0.5
Amount	$ 16,708	$ 0	$ 0	$ 0	$ 0	$ 16,526	$ 16,523	$ 17,216	$ 17,469	$ 12,227	$ 12,224	$ 12,222	$ 16,708	$ 50,265	$ 54,142

Summary of Significant Accounting Policies - Additional Information (Detail) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) Customer shares	Dec. 31, 2022 USD ($) Customer shares	Dec. 31, 2021 USD ($) Customer shares
Significant Accounting Policies [Line Items]
Subsidiary ownership percentage	100.00%
Number of customers accounted for 10% or more sales \| Customer	3	2	2
Depreciation and amortization of property & equipment \| $	$ 21,810	$ 18,931	$ 17,160
Evaluation of tax benefits realized upon settlement	50.00%
Long-term investments \| $	$ 6,500	$ 6,500
Minimum percentage of total income tax paid	5.00%
Minimum
Significant Accounting Policies [Line Items]
Short term investment maturity period	3 months
Maximum
Significant Accounting Policies [Line Items]
Short term investment maturity period	1 year
Net sales \| Customers accounted for 10% or more \| Top Ten Customers [Member]
Significant Accounting Policies [Line Items]
Major customers percentage of net sales	75.00%	81.00%	76.00%
Net sales \| Customers accounted for 10% or more \| Two Customers [Member]
Significant Accounting Policies [Line Items]
Major customers percentage of net sales		45.00%	36.00%
Net sales \| Customers accounted for 10% or more \| Three Customers [Member]
Significant Accounting Policies [Line Items]
Major customers percentage of net sales	45.00%
Employee Stock Option And Restricted Stock Units [Member]
Significant Accounting Policies [Line Items]
The effect of dilutive securities of employee stock options and restricted stock units \| shares	466	526	563
Employee Stock Option And Restricted Stock Units [Member] \| American Depositary Shares [Member]
Significant Accounting Policies [Line Items]
The effect of dilutive securities of employee stock options and restricted stock units \| shares	117	131	141
Software \| Minimum
Significant Accounting Policies [Line Items]
Property plant and equipment estimated useful life	1 year
Software \| Maximum
Significant Accounting Policies [Line Items]
Property plant and equipment estimated useful life	5 years
Buildings \| Minimum
Significant Accounting Policies [Line Items]
Property plant and equipment estimated useful life	25 years
Buildings \| Maximum
Significant Accounting Policies [Line Items]
Property plant and equipment estimated useful life	50 years
Machinery and Equipment \| Minimum
Significant Accounting Policies [Line Items]
Property plant and equipment estimated useful life	2 years
Machinery and Equipment \| Maximum
Significant Accounting Policies [Line Items]
Property plant and equipment estimated useful life	6 years
Furniture and Fixtures \| Minimum
Significant Accounting Policies [Line Items]
Property plant and equipment estimated useful life	3 years
Furniture and Fixtures \| Maximum
Significant Accounting Policies [Line Items]
Property plant and equipment estimated useful life	8 years
Leasehold And Building Improvement \| Minimum
Significant Accounting Policies [Line Items]
Property plant and equipment estimated useful life	2 years
Leasehold And Building Improvement \| Maximum
Significant Accounting Policies [Line Items]
Property plant and equipment estimated useful life	6 years

Refund Liabilities (Tables)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Summary of Change in Refund Liabilities

The changes in the refund liabilities are summarized as follows:


	Year Ended December 31
	2022			2023
	US$			US$
Refund liabilities
Balance, beginning of year		3,882			6,471
Additions		19,196			5,780
Actual sales return and discount		(16,607	)		(8,922	)

Balance, end of year		6,471			3,329

Lease - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Leased Assets [Line Items]
Lease Expense	$ 5,261	$ 4,820	$ 4,574
Operating Lease Payments	3,825	3,642	$ 3,502
Operating lease right of use assets	14,134	$ 8,149
Operating lease liabilities accrued current	2,343
Operating lease liabilitites long term	$ 12,696
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other Liabilities, Noncurrent
Other Noncurrent Liabilities [Member]
Operating Leased Assets [Line Items]
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other Liabilities, Noncurrent	Other Liabilities, Noncurrent
Accounting Standards Update 2016-02 [Member]
Operating Leased Assets [Line Items]
Operating lease right of use assets	$ 14,134	$ 8,149
Operating lease weighted average remaining lease term	8 years 25 days	3 years 1 month 20 days
Operating lease weighted average discount rate	2.56%	2.38%
Accounting Standards Update 2016-02 [Member] \| Other Current Liabilities [Member]
Operating Leased Assets [Line Items]
Operating lease liabilities accrued current	$ 2,343	$ 3,204
Accounting Standards Update 2016-02 [Member] \| Other Noncurrent Liabilities [Member]
Operating Leased Assets [Line Items]
Operating lease liabilitites long term	$ 12,696	$ 4,908

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 52,873	$ 172,510	$ 200,002
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	21,810	18,931	17,160
Loss on pension curtailment or settlement	0	156	0
Loss on modification of lease	230	0	0
Unrealized holding gain on investment	(8,002)	(896)	0
Stock-based compensation	17,547	26,661	19,545
Loss (gain) on disposal of property and equipment	(215)	7	208
Deferred income taxes	428	(2,526)	(1,743)
Changes in operating assets and liabilities:
Accounts receivable	11,404	2,469	(92,749)
Inventories	72,127	(102,846)	(78,095)
Prepaid expenses and other current assets	(6,563)	3,648	1,230
Other assets	705	(974)	35
Notes and accounts payable	19,563	(44,745)	36,233
Refund liabilities	(3,142)	2,589	1,777
Accrued expenses and other current liabilities	(1,634)	676	26,394
Income tax payable	(34,570)	(2,087)	37,315
Other liabilities	6,522	10,319	7,386
Net cash provided by operating activities	149,083	83,892	174,698
CASH FLOWS FROM INVESTING ACTIVITIES
Purchase of long-term investment	0	0	(3,507)
Proceeds from disposal of properties	1,228	0	0
Purchase of property and equipment	(50,313)	(32,942)	(24,657)
Net cash used in investing activities	(49,085)	(32,942)	(28,164)
CASH FLOWS FROM FINANCING ACTIVITIES
Repayments of bank loan	0	(40,000)	0
Proceeds from bank loan	0	40,000	0
Dividends paid	(16,690)	(49,941)	(54,039)
Share repurchase	0	(133,155)	(45,696)
Net cash used in financing activities	(16,690)	(183,096)	(99,735)
NET INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	83,308	(132,146)	46,799
EFFECT OF EXCHANGE RATE CHANGES	(1,373)	3,678	(487)
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH, BEGINNING OF YEAR	287,055	415,523	369,211
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH, END OF YEAR	368,990	287,055	415,523
SUPPLEMENTAL INFORMATION
Interest paid	0	71	0
Income taxes paid	36,316	33,985	3,523
NON-CASH INVESTING AND FINANCING ACTIVITIES:
Unpaid purchase of property and equipment included in accounts payable and accrued liabilities	4,301	4,957	2,281
Dividend declared included in accrued expenses and accrued liabilities	$ 50,147	$ 101	$ 51,681

Cash, Cash Equivalents, and Restricted Cash

12 Months Ended

Dec. 31, 2023

Cash and Cash Equivalents [Abstract]

Cash, Cash Equivalents, and Restricted Cash

3. CASH, CASH EQUIVALENTS, AND RESTRICTED CASH


	December 31
	2022		2023
	US$		US$
Cash and deposits in bank		70,787		46,479
Time deposits		143,267		235,570
Repurchase agreements		18,125		32,253

Total cash and cash equivalents		232,179		314,302
Restricted cash		54,876		54,688

		287,055		368,990

Consolidated Statements Of Changes In Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Ordinary Shares	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings (accumulated deficit)	Treasury Stock
Beginning Balance at Dec. 31, 2020	$ 557,742	$ 1,382	$ 275,132	$ (349)	$ 281,577	$ 0
Beginning Balance, shares at Dec. 31, 2020		138,168
Net income	200,002				200,002
Other comprehensive income (loss)	(191)			(191)
Stock-based compensation expenses	19,545		19,545
Issuance of ordinary shares upon exercise of restricted stock units, shares		1,596
Issuance of ordinary shares upon exercise of restricted stock units	(5)	$ 16	(21)
Share repurchase	(50,011)					(50,011)
Dividends declared	(69,450)				(69,450)
Ending Balance at Dec. 31, 2021	657,632	$ 1,398	294,656	(540)	412,129	(50,011)
Ending Balance, shares at Dec. 31, 2021		139,764
Net income	172,510				172,510
Other comprehensive income (loss)	3,135			3,135
Stock-based compensation expenses	26,661		26,661
Issuance of ordinary shares upon exercise of restricted stock units, shares		1,186
Issuance of ordinary shares upon exercise of restricted stock units	(39)	$ 12	(51)
Share repurchase	(128,840)					(128,840)
Treasury stock retired (Shares)		(8,734)
Treasury stock retired		$ (88)	(17,702)		(161,061)	178,851
Adjustment to dividends paid	1,542				1,542
Ending Balance at Dec. 31, 2022	$ 732,601	$ 1,322	303,564	2,595	425,120	0
Ending Balance, shares at Dec. 31, 2022	132,216	132,216
Net income	$ 52,873				52,873
Other comprehensive income (loss)	(1,442)			(1,442)
Stock-based compensation expenses	17,547		17,547
Issuance of ordinary shares upon exercise of restricted stock units, shares		1,460
Issuance of ordinary shares upon exercise of restricted stock units	(46)	$ 15	(61)
Dividends declared	(66,837)				(66,837)
Ending Balance at Dec. 31, 2023	$ 734,696	$ 1,337	$ 321,050	$ 1,153	$ 411,156	$ 0
Ending Balance, shares at Dec. 31, 2023	133,676	133,676

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Basis of Presentation

The consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The consolidated financial statements include the accounts of SMTC and its wholly-owned subsidiaries. The Company owns 100% of the outstanding shares in all of its subsidiaries. All significant intercompany balances and transactions have been eliminated upon consolidation.

Use of Estimates

The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect certain reported amounts and disclosures. The actual results could differ from those estimates.

Concentration of Credit Risk and Significant Customers

Financial instruments that potentially subject the Company to a significant concentration of credit risk consist principally of cash equivalents and accounts receivable. Cash and cash equivalents are maintained with high quality financial institutions, the composition and maturities of which are regularly monitored by management. The Company believes that the concentration of credit risk in its accounts receivables is substantially mitigated by the Company’s credit evaluation process, relatively short collection terms and the high level of credit worthiness of its customers. The Company performs ongoing credit evaluations of its customers’ financial conditions and limits the amount of credit extended based upon payment history and the customer’s current credit worthiness. The Company regularly reviews the allowance for bad debt and doubtful accounts or expected losses during the accounts receivable collection process by considering factors, such as historical

write-off

and recovery experience, credit quality, age of the accounts receivable balances and current economic conditions that may affect a customer’s ability to pay. The Company also takes into account reasonable and supportable forecasts of future conditions when evaluating the adequacy of the allowance for doubtful accounts.

Historically, a relatively small number of customers have accounted for a significant portion of our net sales. Sales to two customers in 2021, and in 2022 and

three

customers in 2023 accounted for 10% or more of our net revenue, representing 36%, 45% and 45% of our net sales in 2021, 2022 and 2023, respectively. In 2021, the significant customers were Intel and Micron and in 2022, they were Micron and SK Hynix. In 2023, they were SK Hynix, Micron and AFASTOR. The Company’s top ten customers in 2021, 2022 and 2023 accounted for approximately 76%, 81% and 75% of net sales, respectively.

Fair Value of Financial Instruments

The carrying amount of the Company’s financial instruments, including cash and cash equivalents, accounts receivable and notes and accounts payables approximates fair value due to the short-term maturity of the instruments. Long-term investments in listed companies over which we do not exercise significant influence are recorded at fair value, and any changes in fair value are recognized in net income. Long-term investments in privately-held companies with no readily determinable market value are recorded using the cost method, since the cost of obtaining verifiable fair value is unreasonably high. These investments are measured at cost less impairment, if any, plus or minus any changes resulting from observable price changes in orderly transactions for an identical or similar investment of the same issuer. Any resulting change in carrying amount would be reflected in net income. The Company’s long-term liabilities approximate their fair values as they contain interest rates that vary according to market interest rates.

Fair value is the price that would be received upon sale of an asset or paid upon transfer of a liability in an orderly transaction between market participants at the measurement date and in the principal or most advantageous market for that assets or liability. The fair value should be calculated based on assumptions that market participants would use in pricing the asset or liability, not on assumptions specific to the Company. A three-tier fair value hierarchy is established as a basis for considering such assumptions and for inputs used in the valuation methodologies in measuring fair value. The hierarchy prioritizes the inputs into three levels based on the extent to which inputs used in measuring fair value are observable in the market. Each fair value measurement is reported in one of the three levels which is determined by the lowest level input that is significant to the fair value measurement in its entirety. These levels are:

Level 1 — Use unadjusted quoted prices in active markets for identical assets or liabilities.

Level 2 — Use observable inputs other than Level 1 prices such as quoted prices for identical or similar instruments in markets that are not active, quoted prices for similar instruments in active markets, and model-based valuation in which all significant inputs are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3 — Use inputs that are generally unobservable and reflect the use of significant management judgments and estimates.

The tables below set forth, by level, the Company’s assets and liabilities that are measured at fair value on a recurring basis. The tables do not include assets and liabilities that are measured at historical cost or any basis other than fair value:


	Fair Value Measurements at December 31, 2023
	Level 1		Level 2		Level 3		Total
Items measured at fair value on a recurring basis:
Assets
Long-term investments:
Marketable equity investments	$	10,616		—		—	$	10,616


	Fair Value Measurements at December 31, 2022
	Level 1		Level 2		Level 3		Total
Items measured at fair value on a recurring basis:
Assets
Long-term investments:
Marketable equity investments	$	2,767		—		—	$	2,767

The carrying value of investments in

non-marketable

equity securities recorded to fair value on a

non-recurring

basis is adjusted for observable transactions for identical or similar investments of the same issuer or for impairment. These securities relate to equity investments in privately-held companies. These items measured at fair value on a

non-recurring

basis are classified as Level 3 in the fair value hierarchy because the value is estimated based on valuation methods using the observable transaction price at the transaction date and other unobservable inputs such as volatility, rights and obligations of the securities held. As of December 31, 2022 and 2023,

non-marketable

equity investments had a carrying value of $6,500 thousand and $6,500 thousand, respectively, and are included in long-term investments in the Company’s consolidated balance sheets.

Cash Equivalents

The Company considers all highly liquid instruments acquired with a remaining maturity of three months or less when purchased to be cash equivalents. In addition, time deposits with maturities ranging from more than three months to one year qualify as cash equivalents because they can be readily converted into known amounts of cash without advance notice with the principal protected and not subject to penalty in an early withdrawal.

Allowance for Doubtful Accounts

An allowance for doubtful accounts is provided based on a review of the collectability of accounts receivables. The Company determines the amount of allowance for doubtful accounts by examining the historical collection experience, current trends in the credit quality of its customers and its internal credit policies as well as current economic conditions, reasonable and supportable forecasts of future economic conditions, and other factors that may affect a customer’s ability to pay.

Inventories

Inventories are stated at the lower of cost or net realizable value for raw materials, work in process and finished goods. Inventories are recorded at standard cost and adjusted to the approximate weighted-average cost at the balance sheet date. The Company assesses its net realizable value of the inventory for estimated obsolescence or unmarketable inventory based upon management’s assumptions about future demand and market

conditions. In estimating impairment losses for obsolescence, the Company primarily evaluates estimates based on the timing of the introduction of new products and the quantities remaining of old products and write down for inventory on hand in excess of the estimated demand. Estimated losses on slow-moving items are written down below the current carrying value and included in cost of

sales

Long-term Investments

Investee companies over which the Company had the ability to exercise significant influence but did not have a controlling interest and was the primary beneficiary were accounted for using the equity method. Significant influence was generally considered to exist when the Company had an ownership interest in the voting shares of the investee between 20% and 50% and other factors, such as representation in the investee’s board of directors, voting rights and the impact of commercial arrangements, were considered in determining whether the equity method of accounting was appropriate.

Long-term investments in listed companies over which we do not exercise significant influence are recorded at fair value, and any changes in fair value are recognized in net income. If the Company does not have the ability to exercise significant influence over the operations of the investments in private-held companies, the Company accounts for the investment under the measurement alternative method. Investments in privately-held companies are subject to impairment review on an ongoing basis. Investments are considered impaired when the fair value is below the investment’s cost basis. This assessment is based on a qualitative and quantitative analysis, including, but not limited to, the investee’s revenue and earnings trends, available cash and liquidity, and the status of the investee’s products and the related market for such products.

Property and Equipment

Property and equipment are stated at cost less accumulated depreciation. Significant additions, renewals and betterments are capitalized, while maintenance and repairs are expensed as incurred.

Depreciation is computed using the straight-line method over estimated useful lives that range as follows: buildings — 25 to 50 years; machinery and equipment — 2 to 6 years; furniture and fixtures — 3 to 8 years; software — 1 to 5 years; leasehold and buildings improvement — the shorter of the estimated useful life or lease term, which is generally 2 to

years. Land is not depreciated. Depreciation and amortization expense on property and equipment were approximately US$17,160 thousand, US$18,931 thousand and US$21,810 thousand for the years ended December 31, 2021, 2022 and 2023, respectively.

Lease

The Company determines if an arrangement is a lease at inception. Operating

lease right-of-use (“ROU”)

assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. Operating lease ROU assets also include any initial direct costs and prepayments less lease incentives. Lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise such options. As the Company’s leases do not provide an implicit rate, the Company uses its collateralized incremental borrowing rate based on the information available at the lease commencement date, including lease term, in determining the present value of lease payments. Lease expense for these leases is recognized on a straight line basis over the lease term.

Impairment of Long-Lived Assets

The Company evaluates the recoverability of long-lived assets whenever events or changes in circumstances indicate the carrying value may not be recoverable. The determination of recoverability is based on an estimate of undiscounted cash flows expected to result from the use of an asset and its eventual disposition. The estimate of cash flows is based upon, among other things, certain assumptions about expected future operating

performance, growth rates and other factors. Estimates of undiscounted cash flows may differ from actual cash flows due to, among other things, technological changes, economic conditions, changes to the business model or changes in operating performance. If the sum of the undiscounted cash flows is less than the carrying value, an impairment loss is recognized, measured as the amount by which the carrying value exceeds the fair value of the asset. Fair value is determined by reference to quoted market prices, if available, or discounted

cash

flows, as appropriate.

Other Assets

Other assets primarily consist of deposits for building construction and office leases.

Restricted Assets

Restricted assets consist of restricted cash and cash set aside as collateral for obtaining foundry capacity.

Other long-term liabilities

Other long-term liabilities primarily consist of deposit from construction in progress, noncurrent lease liabilities and unrecognized tax benefit.

Revenue Recognition

The Company recognizes revenue upon transfer of control of promised products or services to customers in an amount that reflects the consideration the Company expects to receive in exchange for those products or services. Under the revenue recognition standard of Accounting Standards Codification Topic 606, Revenue from Contracts with Customer (ASC 606), the Company applies the following five-step approach: (1) identify the contract with a customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract, and (5) recognize revenue when a performance obligation is satisfied.

The Company enters into contracts that may include products that are capable of being distinct and accounted for as separate performance obligations. To date, the majority of the revenue has been generated by sales associated with products, where a single performance obligation is identified in general. Revenue from services has been insignificant. Performance obligations associated with product sales transactions are generally satisfied when control passes to customers upon shipment or the written acceptance of the customers. Accordingly, product revenue is recognized at a point in time when control of the asset is transferred to the customer. The Company recognizes revenue when it satisfies a performance obligation by transferring control of a product to a customer in an amount that reflects the consideration to which it is entitled in exchange for those goods. Some of the Company’s sales are made to distributors and revenue is recognized when control of a product passes to the distributor upon shipment and terms and payment by the distributor are not contingent on resale of the product.

The Company grants certain distributors limited rights of return and price protection rights on unsold products. The return rights are generally limited to five percent of the monetary value of products purchased within the preceding six months, provided that the distributor places a corresponding restocking order of equal or greater value. An allowance for sales returns for distributors and all customers is recorded at the time of sale based on historical returns information available, management’s judgment and any known factors at the time the financial statements are prepared that would significantly affect the allowance. Price protection rights are based on the inventory of products the distributors have on hand at the date the price protection is offered. Actual price adjustments to distributors incurred by the Company have been minimal.

The Company provides warranty for its products. Warranty returns have been infrequent and relate to defective

or off-specification parts.

The Company estimates a reserve for warranty based on historical experience

and records this amount to cost of sales. For the years ended December 31, 2021, 2022 and 2023, the Company did not experience significant costs associated with warranty

returns

Research and Development

Research and development costs are expensed as incurred. Research and development expense consists primarily of personnel-related expenses, including stock-based compensation, as well as product masks, IP licensing, design tool and testing costs, equipment depreciation, amortization of intangible assets and an allocated portion of occupancy costs.

Income Taxes

The provision for income tax represents income tax paid and payable for the current year plus changes in the deferred income tax assets and liabilities during the years. Deferred income tax assets are recognized for net operating loss carryforwards, research and development credits, and temporary differences. The Company establishes a valuation allowance for deferred tax assets, when it is determined that it is more likely than not that they will not be realized. Evaluating the need for a valuation allowance on deferred tax assets requires judgment and analysis of all available positive and negative evidence, including recent earnings history and cumulative losses in recent years, reversals of deferred tax liabilities, projected future taxable income, and tax planning strategies to determine whether all or some portion of the deferred tax assets will not be realized. Valuation allowances have been provided primarily against U.S. and state research and development credits and certain acquired net operating losses and deferred tax assets of foreign subsidiaries. Deferred income tax assets and liabilities are measured using enacted tax rates.

The Company utilizes a two steps approach to recognizing and measuring uncertain tax positions. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates it is more likely than not that the position will be sustained in a dispute with taxing authorities, including resolution of related appeals or litigation processes, if any. The second step is to measure the tax benefit as the largest amount which is more than 50% likely of being realized upon ultimate settlement. Changes in recognition or measurement are reflected in the period in which the change in judgment occurs. The Company records interest and penalties related to unrecognized tax benefits in income tax expense.

Foreign Currency Transactions

Foreign currency transactions are recorded at the rates of exchange in effect when the transaction occurs. Gains or losses, resulting from the application of different foreign exchange rates when cash in foreign currency is converted into the entities’ functional currency, or when foreign currency receivables and payables are settled, are credited or charged to income in the period of conversion or settlement. At the balance sheet date, assets and liabilities denominated in foreign currencies are remeasured based on prevailing exchange rates and any resulting gains or losses are credited or charged to income.

Translation of Foreign Currency Financial Statements

The reporting currency of the Company is the U.S. dollars. The functional currency of some of the Company’s subsidiaries is the local currency of the respective entity. Accordingly, the financial statements of the foreign subsidiaries were translated into U.S. dollars at the following exchange rates: assets and liabilities — current rate on the balance sheet date; shareholders’ equity — historical rates; income and expenses — average rate during the period. The resulting translation adjustment is recorded as a separate component of comprehensive income.

Comprehensive Income (Loss)

Comprehensive income and loss represents net income (loss) plus the results of certain changes in shareholders’ equity during a period from

non-owner

sources. The following table presents the components of accumulated other comprehensive income (loss) as of December 31, 2021, 2022 and 2023:


	Year Ended December 31, 2021									Year Ended December 31, 2022								Year Ended December 31, 2023
	US$									US$								US$
	Foreign currency items			Defined benefit pension plans			Accumulated other comprehensive income (loss)			Foreign currency items		Defined benefit pension plans			Accumulated other comprehensive income (loss)			Foreign currency items			Defined benefit pension plans			Accumulated other comprehensive income (loss)
Beginning balance		405			(754	)		(349	)		178		(718	)		(540	)		3,917			(1,322	)		2,595
Current-period change		(227	)		36			(191	)		3,739		(604	)		3,135			(1,694	)		252			(1,442	)

Ending balance		178			(718	)		(540	)		3,917		(1,322	)		2,595			2,223			(1,070	)		1,153

Legal Contingencies

The Company is regularly involved in various claims and legal proceedings. Periodically, the Company reviews the status of each significant matter and assesses the potential financial exposure. Legal costs are expensed as incurred. If the potential loss from any claim or legal proceeding is considered probable and the amount can be estimated, the Company accrues a liability for the estimated loss. Because of uncertainties related to these matters, accruals are based only on the best information available at the time. As additional information becomes available, the Company reassesses the potential liability related to the pending claims and litigation and revises these estimates as appropriate. Such revisions in the estimates of the potential liabilities could have a material impact on the results of operations and financial position. Contingencies that might result in a gain are not recognized until realizable.

Earnings Per Share

Basic earnings per share are computed by dividing net earnings attributable to ordinary shareholders by the weighted-average number of ordinary shares outstanding during the period. Diluted earnings per share are computed by dividing net income attributable to ordinary shareholders by the weighted-average number of ordinary shares and

potentially dilutive shares of ordinary shares outstanding during the period. Dilutive shares outstanding include unvested restricted stock units (“RSUs”). Dilutive securities are excluded from the computation of the diluted income per share in periods when their effect is anti-dilutive. The effect of dilutive securities of restricted stock units were

563

thousand shares (

141

thousand ADSs),

526

thousand shares (

131

thousand ADSs) and 466 thousand shares (117 thousand ADSs) for the years ended December 31, 2021, 2022 and 2023, respectively.

Stock-Based Compensation

The Company accounts for stock-based compensation in accordance with the Accounting Standards Codification (“ASC”) 718 Compensation — Stock Compensation. The value of our restricted stock units is based on the fair value of our shares on the date of grant and expensed over the vesting period.

The fair value of RSUs is measured based on the grant date share price, less the present value of expected dividends during the vesting period, discounted at a risk-free interest rate.

Treasury Stock

Treasury stock is stated at cost and shown as a reduction to shareholders’ equity.

The Company retires ordinary shares repurchased. Accordingly, upon retirement the excess of the purchase price over par value is allocated between additional

paid-in

capital and retained earnings based on the average issuance price of the shares repurchased. A repurchase of ADSs is recorded as treasury stock until the Company completes the withdrawal of the underlying ordinary shares

from

the ADS program.

Recent Accounting Pronouncements

In July 2023, the Financial Accounting Standards Board (“FASB”) issued an accounting standard update (ASU), ASU

2023-03,

Presentation of Financial Statements (Topic 205), Income Statement—Reporting Comprehensive Income (Topic 220), Distinguishing Liabilities from Equity (Topic 480), Equity (Topic 505), and Compensation—Stock Compensation (Topic 718): Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 120, SEC Staff Announcement at the March 24, 2022 EITF Meeting, and Staff Accounting Bulletin Topic 6.B, Accounting Series Release 280—General Revision of Regulation

S-X:

Income or Loss Applicable to Common Stock (SEC Update). This ASU amends or supersedes various SEC paragraphs within the codification to conform to past announcements and guidance issued by the SEC. The adoption of this amendment did not have a material impact on the Company’s results of operations, financial position, cash flows or financial statement disclosures.

In October 2023, the Financial Accounting Standards Board (“FASB”) issued an accounting standard update (ASU), ASU

2023-06,

Disclosure Improvements: Codification Amendments in Response to the SEC’s Disclosure Update and Simplification Initiative, to amend certain disclosure and presentation requirements for a variety of topics within the ASC. These amendments align the requirements in the ASC to the removal of certain disclosure requirements set out in Regulation

S-X

and Regulation

S-K,

announced by the SEC. The effective date for each amended topic in the ASC is either the date on which the SEC’s removal of the related disclosure requirement from Regulation

S-X

or Regulation

S-K

becomes effective, or on June 30, 2027, if the SEC has not removed the requirements by that date. Early adoption is prohibited. The adoption of this amendment is not expected to have a material impact on the Company’s financial position, results of operations, cash flows or financial statement disclosures.

In November 2023, the FASB issued an accounting standard update (ASU), ASU

No. 2023-07,

Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, which updates reportable segment disclosure requirements primarily through enhanced disclosures about significant segment expenses. The amendments are effective for fiscal years beginning after December 15, 2023, and for interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. The amendments should be applied retrospectively to all prior periods presented in the financial statements. The Company is currently evaluating the impact that the adoption will have on its results of operations, financial position, cash flows and financial statement disclosures.

In December 2023, the Financial Accounting Standards Board (“FASB”) issued an accounting standard update (ASU), ASU

2023-09,

Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which requires a public business entity to disclose specific categories in its annual effective tax rate reconciliation and disaggregated information about significant reconciling items by jurisdiction and by nature. The ASU also requires entities to disclose their income tax payments (net of refunds received) to international, federal, and state and local jurisdictions in which income taxes paid (net of refunds received) is equal to or greater than 5 percent of total income taxes paid (net of refunds received). The guidance makes several other changes to income tax disclosure requirements. This guidance is effective for fiscal years beginning after December 15, 2024 and requires prospective application with the option to apply it retrospectively. Early adoption is permitted. The Company is currently evaluating the impact that the adoption will have on its results of operations, financial position, cash flows and financial statement disclosures.

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Summary of the Company's Assets and Liabilities that are Measured at Fair Value on a Recurring Basis


	Fair Value Measurements at December 31, 2023
	Level 1		Level 2		Level 3		Total
Items measured at fair value on a recurring basis:
Assets
Long-term investments:
Marketable equity investments	$	10,616		—		—	$	10,616


	Fair Value Measurements at December 31, 2022
	Level 1		Level 2		Level 3		Total
Items measured at fair value on a recurring basis:
Assets
Long-term investments:
Marketable equity investments	$	2,767		—		—	$	2,767

Components of Accumulated Other Comprehensive Income (Loss)

The following table presents the components of accumulated other comprehensive income (loss) as of December 31, 2021, 2022 and 2023:


	Year Ended December 31, 2021									Year Ended December 31, 2022								Year Ended December 31, 2023
	US$									US$								US$
	Foreign currency items			Defined benefit pension plans			Accumulated other comprehensive income (loss)			Foreign currency items		Defined benefit pension plans			Accumulated other comprehensive income (loss)			Foreign currency items			Defined benefit pension plans			Accumulated other comprehensive income (loss)
Beginning balance		405			(754	)		(349	)		178		(718	)		(540	)		3,917			(1,322	)		2,595
Current-period change		(227	)		36			(191	)		3,739		(604	)		3,135			(1,694	)		252			(1,442	)

Ending balance		178			(718	)		(540	)		3,917		(1,322	)		2,595			2,223			(1,070	)		1,153

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Income (Loss) Before Income Taxes for Cayman and Non-Cayman Entities

The income (loss) before taxes for Cayman and

Non-Cayman

entities is as follows:


	Year Ended December 31
	2021			2022			2023
	US$			US$			US$
Cayman		(22,847	)		(39,449	)		(17,082	)
Non-Cayman		270,111			252,027			78,130

Income before taxes		247,264			212,578			61,048

Components of Income Tax Expense

The components of income tax provision (benefit) were as follows:


	Year Ended December 31
	2021			2022			2023
	US$			US$			US$
Current		49,005			42,594			7,747
Deferred		(1,743	)		(2,526	)		428

Income tax expense		47,262			40,068			8,175


Effective tax rate		19.1	%		18.8	%		13.4	%

Reconciliation of Income Tax Expense on Pretax Income at Statutory Rate and Income Tax Expense

A reconciliation of its income tax expense at the statutory rate and provision for income tax is shown below:


	Year Ended December 31
	2021			2022			2023
	US$			US$			US$
Tax expense at Cayman statutory rate		—			—			—
Differences between Cayman and other statutory tax rates		48,322			38,696			9,979
Permanent differences		(10,625	)		(3,377	)		206
Temporary differences		(400	)		(1,091	)		(1,614	)
Alternative minimum tax		1			1			1
Income tax on undistributed earnings		3,609			1,874			—
Net changes in income tax credit		1,261			(38	)		(205	)
Net changes in valuation allowance of deferred income tax assets		1,066			(302	)		3,260
Net operating loss carryforwards		180			1,668			(1,805	)
Liabilities related to unrealized tax benefits		5,877			11,036			5,482
Adjustment of prior years’ taxes and others		(2,029	)		(8,399	)		(7,129	)

Income tax expense		47,262			40,068			8,175

Deferred Income Tax Assets (Liabilities)

Significant components of our deferred tax assets (liabilities) at the end of each period are as follows:


	December 31
	2022			2023
	US$			US$
Stock-based compensation		3,058			1,430
Allowance for sales return		1,000			392
Inventory reserve		2,428			2,983
Foreign currency translation		(48	)		(35	)
Property and equipment		(576	)		(1,076	)
Investment tax credits		3,290			3,495
Net operating loss carryforwards		18,057			21,332
Others		1,838			3,055
Valuation allowance		(20,163	)		(23,120	)

Net deferred tax assets		8,884			8,456

Reconciliation of Unrecognized Tax Benefits

A reconciliation of the beginning and ending balances of the total amounts of unrecognized tax benefits is as follows:


	Year Ended December 31
	2021			2022			2023
	US$			US$			US$
Balance, beginning of year		19,001			26,317			37,105
Increases in tax positions taken in current year		8,750			13,705			16,054
Decrease in tax position taken in prior year primarily related to the resolution of tax audit		(1,434	)		(2,917	)		(9,395	)

Balance, end of year		26,317			37,105			43,764

Summary of Major Jurisdictions and Tax Year Subject to Examination by Tax Authorities


Tax Jurisdiction		Tax Years
China		2020 and onward
Hong Kong		2020 and onward
Taiwan		2018 and onward
United States		2018 onward

Lease (Tables)

12 Months Ended

Dec. 31, 2023

Leases [Abstract]

Summary of Future Lease Payments for the Operating Leases Under the Operating Leases

The aggregate future lease payments for the operating leases under the operating leases as of December 31, 2023, were as follows:


	Operating Lease Obligations
Fiscal Year:
2024	$	2,687
2025		2,329
2026		2,010
2027		1,522
2028		1,303
2029 and thereafter		6,688

Total		16,539
Less imputed interest		1,500

Present value of lease liabilities		15,039
Less operating lease liabilities-current		2,343

Long-term operating lease liabilities	$	12,696

Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 52,873	$ 172,510	$ 200,002
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX EFFECT OF NIL
Change in net foreign currency translation adjustments	(1,694)	3,739	(227)
Change in deferred pension gain (loss)	252	(604)	36
OTHER COMPREHENSIVE INCOME (LOSS)	(1,442)	3,135	(191)
TOTAL COMPREHENSIVE INCOME	$ 51,431	$ 175,645	$ 199,811

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

- Definition

Amount after tax and reclassification adjustments of other comprehensive income (loss).

+ References

+ Details

Long-Term Investments (Tables)

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Long-Term Investments

As of December 31, 2022 and 2023, the Company held equity investments in several privately-held companies with the carrying value as follows:


	Percentage of Ownership						December 31
	2022			2023			2022		2023
							US$		US$
Non-marketable equity securities:
Cashido Corp . (Cashido)		0.6	%		0.6	%		—		—
Vastview Technology, Corp. (Vastview)		2.9	%		2.9	%		—		—
Kinara, Inc (Kinara)		14.1	%		14.1	%		6,500		6,500

								6,500		6,500
Marketable equity securities:
BIWIN Storage Technology Corp.(BIWIN)		0.3	%		0.3	%		2,767		10,616

								9,267		17,116

Refund Liabilities

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Refund Liabilities

9. REFUND LIABILITIES

Estimated sales returns and other allowances are made and adjusted based on historical experience and the consideration of varying contractual terms.

The changes in the refund liabilities are summarized as follows:


	Year Ended December 31
	2022			2023
	US$			US$
Refund liabilities
Balance, beginning of year		3,882			6,471
Additions		19,196			5,780
Actual sales return and discount		(16,607	)		(8,922	)

Balance, end of year		6,471			3,329

Other Changes in Plan Assets and Benefit Obligation Recognized in Other Comprehensive Loss (Income) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Other Changes in Plan Assets and Benefit Obligation Recognized in Other Comprehensive Income (Loss):
Recognize the decrease in net gain (loss)	$ (252)	$ 604	$ (36)
Total recognized in other comprehensive loss (income)	$ (252)	$ 604	$ (36)

Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Net Periodic Benefit Cost:
Service cost	$ 19	$ 13	$ 35
Interest cost	8	14	20
Projected return on plan assets	(17)	(30)	(33)
Amortization of unrecognized net transition obligation and unrecognized net actuarial gain	24	35	34
Curtailment or settlement loss	0	156	0
Net periodic benefit cost	$ 34	$ 188	$ 56
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest Expense	Interest Expense	Interest Expense

Summary of Status of Restricted Stock Units and Changes (Detail) - Restricted Stock Units - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Number of Nonvested Stock Units
Nonvested at beginning period	1,977	2,310	1,714
Restricted stock units granted	624	902	2,326
Restricted stock units vested	(1,460)	(1,186)	(1,596)
Restricted stock units forfeited	(51)	(49)	(134)
Nonvested at ending period	1,090	1,977	2,310	1,714
Weighted Average Grant Date Fair Value
Nonvested at beginning period	$ 17.89	$ 17.37	$ 9.37
Restricted stock units granted	13.51	19.56	17.62
Restricted stock units vested	18.36	17.61	9.31
Restricted stock units forfeited	16.38	17.18	14.99
Nonvested at ending period	$ 15	$ 17.89	$ 17.37	$ 9.37
Weighted Average Remaining Recognition Period (Years)
Nonvested at ending period	1 month 17 days	7 months 28 days	1 year 6 months 25 days	3 months 21 days

Equity Incentive Plan - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jun. 03, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Tax effect for stock-based compensation benefit (expense) for option and restricted stock units exercised	$ (178)	$ 2	$ (155)
Employee Stock Options And Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Tax effect for stock-based compensation benefit (expense) for option and restricted stock units exercised	$ 4,925	$ 3,957	$ 2,767
2015 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ordinary shares authorized				20,000,000
2015 Equity Incentive Plan \| Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Conversion ratio of restricted stock unit to ordinary shares	one-for-one basis
The 2005 Plan and The 2015 Plan \| Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost related to non-vested share-based compensation	$ 2,076

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Summary of Significant Accounting Policies - Summary of the Company's Assets and Liabilities that are Measured at Fair Value on a Recurring Basis (Detail) - Fair Value, Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable equity investments	$ 10,616	$ 2,767
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable equity investments	10,616	2,767
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable equity investments	0	0
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable equity investments	$ 0	$ 0

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Basis of Presentation

Use of Estimates

Concentration of Credit Risk and Significant Customers

write-off

Historically, a relatively small number of customers have accounted for a significant portion of our net sales. Sales to two customers in 2021, and in 2022 and

three

Fair Value of Financial Instruments

Level 1 — Use unadjusted quoted prices in active markets for identical assets or liabilities.

Level 3 — Use inputs that are generally unobservable and reflect the use of significant management judgments and estimates.


	Fair Value Measurements at December 31, 2023
	Level 1		Level 2		Level 3		Total
Items measured at fair value on a recurring basis:
Assets
Long-term investments:
Marketable equity investments	$	10,616		—		—	$	10,616


	Fair Value Measurements at December 31, 2022
	Level 1		Level 2		Level 3		Total
Items measured at fair value on a recurring basis:
Assets
Long-term investments:
Marketable equity investments	$	2,767		—		—	$	2,767

The carrying value of investments in

non-marketable

equity securities recorded to fair value on a

non-recurring

non-marketable

equity investments had a carrying value of $6,500 thousand and $6,500 thousand, respectively, and are included in long-term investments in the Company’s consolidated balance sheets.

Cash Equivalents

Allowance for Doubtful Accounts

Inventories

sales

Long-term Investments

Property and Equipment

Property and equipment are stated at cost less accumulated depreciation. Significant additions, renewals and betterments are capitalized, while maintenance and repairs are expensed as incurred.

Lease

The Company determines if an arrangement is a lease at inception. Operating

lease right-of-use (“ROU”)

Impairment of Long-Lived Assets

cash

flows, as appropriate.

Other Assets

Other assets primarily consist of deposits for building construction and office leases.

Restricted Assets

Restricted assets consist of restricted cash and cash set aside as collateral for obtaining foundry capacity.

Other long-term liabilities

Other long-term liabilities primarily consist of deposit from construction in progress, noncurrent lease liabilities and unrecognized tax benefit.

Revenue Recognition

The Company provides warranty for its products. Warranty returns have been infrequent and relate to defective

or off-specification parts.

The Company estimates a reserve for warranty based on historical experience

and records this amount to cost of sales. For the years ended December 31, 2021, 2022 and 2023, the Company did not experience significant costs associated with warranty

returns

Research and Development

Income Taxes

Foreign Currency Transactions

Translation of Foreign Currency Financial Statements

Comprehensive Income (Loss)

Comprehensive income and loss represents net income (loss) plus the results of certain changes in shareholders’ equity during a period from

non-owner

sources. The following table presents the components of accumulated other comprehensive income (loss) as of December 31, 2021, 2022 and 2023:


	Year Ended December 31, 2021									Year Ended December 31, 2022								Year Ended December 31, 2023
	US$									US$								US$
	Foreign currency items			Defined benefit pension plans			Accumulated other comprehensive income (loss)			Foreign currency items		Defined benefit pension plans			Accumulated other comprehensive income (loss)			Foreign currency items			Defined benefit pension plans			Accumulated other comprehensive income (loss)
Beginning balance		405			(754	)		(349	)		178		(718	)		(540	)		3,917			(1,322	)		2,595
Current-period change		(227	)		36			(191	)		3,739		(604	)		3,135			(1,694	)		252			(1,442	)

Ending balance		178			(718	)		(540	)		3,917		(1,322	)		2,595			2,223			(1,070	)		1,153

Legal Contingencies

Earnings Per Share

563

thousand shares (

141

thousand ADSs),

526

thousand shares (

131

thousand ADSs) and 466 thousand shares (117 thousand ADSs) for the years ended December 31, 2021, 2022 and 2023, respectively.

Stock-Based Compensation

The fair value of RSUs is measured based on the grant date share price, less the present value of expected dividends during the vesting period, discounted at a risk-free interest rate.

Treasury Stock

Treasury stock is stated at cost and shown as a reduction to shareholders’ equity.

The Company retires ordinary shares repurchased. Accordingly, upon retirement the excess of the purchase price over par value is allocated between additional

paid-in

from

the ADS program.

Recent Accounting Pronouncements

In July 2023, the Financial Accounting Standards Board (“FASB”) issued an accounting standard update (ASU), ASU

2023-03,

S-X:

In October 2023, the Financial Accounting Standards Board (“FASB”) issued an accounting standard update (ASU), ASU

2023-06,

S-X

and Regulation

S-K,

announced by the SEC. The effective date for each amended topic in the ASC is either the date on which the SEC’s removal of the related disclosure requirement from Regulation

S-X

or Regulation

S-K

In November 2023, the FASB issued an accounting standard update (ASU), ASU

No. 2023-07,

In December 2023, the Financial Accounting Standards Board (“FASB”) issued an accounting standard update (ASU), ASU

2023-09,

Segment Information

12 Months Ended

Dec. 31, 2023

Segment Reporting [Abstract]

Segment Information

17. SEGMENT INFORMATION

The Company is the global leader and pioneer in developing NAND flash controllers for solid state storage devices. The Company currently operates as one

reportable segment. The chief operating decision maker (“CODM”) is the Chief Executive Officer. The fact that the Company operates in only one reportable segment

s because the decisions on allocation of r

esources

and other operational decisions are made by the CO

M based on his direct involvement with the Company’s operations and product development.

The Company groups its products into two categories, based on the markets in which they may be used. The following summarizes the Company’s revenue by product category:


	Year Ended December 31
	2021		2022		2023
	US$		US$		US$
Mobile Storage		910,569		926,760		632,813
Others		11,531		19,161		6,329

		922,100		945,921		639,142

Revenue is attributed to a geographic area based on the

bill-to

location and is summarized as follows:


	Year Ended December 31
	2021		2022		2023
	US$		US$		US$
Taiwan		159,575		156,205		74,284
United States		53,517		128,844		55,504
Korea		21,569		113,757		48,633
China		286,605		248,301		229,037
Malaysia		73,264		26,375		1,736
Singapore		219,214		141,383		127,642
Others		108,356		131,056		102,306

	922,100		945,921		639,142

Major customers representing at least 10% of net sales are as follows:


	Year Ended December 31
	2021				2022				2023
	US$		%		US$		%		US$		%
Intel		94,781		10		*		*		*		*
Micron		243,204		26		235,934		25		144,011		22
SK Hynix		*		*		191,873		20		75,836		12
AFASTOR		*		*		*		*		70,046		11

*	Less than 10 %

Long-lived assets (property and equipment, net) by geographic area are as follows:


	Year Ended December 31
	2021		2022		2023
	US$		US$		US$
Taiwan		111,341		127,733		155,334
China		12,518		11,028		11,118
Others		619		673		965

		124,478		139,434		167,417

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-15

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 31
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-31

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-42

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Section 50
-Paragraph 32
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-40

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-Name Accounting Standards Codification
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-URI https://asc.fasb.org//280/tableOfContent

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 26
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-26

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Paragraph 34
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-34

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-41

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (a)
-Publisher FASB
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Section 50
-Paragraph 21
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-21

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

+ Details

Cover Page	12 Months Ended
Cover Page	Dec. 31, 2023 shares
Document Information [Line Items]
Document Type	20-F
Amendment Flag	false
Document Period End Date	Dec. 31, 2023
Document Fiscal Year Focus	2023
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	FY
Entity Registrant Name	Silicon Motion Technology Corporation
Entity Filer Category	Large Accelerated Filer
Entity File Number	000-51380
Entity Well-known Seasoned Issuer	Yes
Document Annual Report	true
Document Transition Report	false
Document Shell Company Report	false
Document Registration Statement	false
Document Accounting Standard	U.S. GAAP
Entity Shell Company	false
Entity Voluntary Filers	No
Entity Emerging Growth Company	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Address, Address Line One	Flat C, 19/F, Wing Cheong Commercial Building
Entity Address, Address Line Two	Nos 19-25 Jervois Street
Entity Address, Country	HK
Entity Central Index Key	0001329394
Entity Address, City or Town	Hong Kong Island
Entity Incorporation, State or Country Code	E9
Entity Common Stock, Shares Outstanding	133,675,940
Entity Address, Postal Zip Code	0000
ICFR Auditor Attestation Flag	true
Auditor Name	Deloitte & Touche
Auditor Firm ID	1060
Auditor Location	Taipei, Taiwan
Document Financial Statement Error Correction [Flag]	false
American Depositary Shares [Member]
Document Information [Line Items]
Security Exchange Name	NASDAQ
Title of 12(b) Security	American Depositary Shares, each representing four ordinary shares
Trading Symbol	SIMO
Ordinary shares[Member]
Document Information [Line Items]
Title of 12(b) Security	Ordinary shares, US$0.01 par value per share
No Trading Symbol Flag	true
Business Contact [Member]
Document Information [Line Items]
Entity Address, Address Line One	690 N. McCarthy Blvd. Suite 200
Entity Address, Country	US
Entity Address, City or Town	Milpitas
Entity Address, State or Province	CA
Contact Personnel Fax Number	1 408 519 7101
Country Region	1
City Area Code	408
Local Phone Number	519 7200
Entity Address, Postal Zip Code	95035
Contact Personnel Name	Jason Tsai, Interim

Inventories - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Inventory Disclosure [Abstract]
Inventory written down	$ 7,920	$ 15,833	$ 5,689

Revenue by Product Category (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
NET SALES	$ 639,142	$ 945,921	$ 922,100
Mobile Storage
Segment Reporting Information [Line Items]
NET SALES	632,813	926,760	910,569
Others
Segment Reporting Information [Line Items]
NET SALES	$ 6,329	$ 19,161	$ 11,531

- Definition

+ References

+ Details

Shareholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands			3 Months Ended												12 Months Ended
	Oct. 30, 2023	Oct. 25, 2021	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Nov. 21, 2018
Retained Earnings Adjustments [Line Items]
Dividend declared			$ 0.125	$ 0	$ 0	$ 0	$ 0	$ 0.125	$ 0.125	$ 0.125	$ 0.125	$ 0.0875	$ 0.0875	$ 0.0875	$ 0.5		$ 0.5
Annual Dividend [Member]
Retained Earnings Adjustments [Line Items]
Dividend declared	$ 2	$ 2
Quarterly Dividend [Member]
Retained Earnings Adjustments [Line Items]
Dividend declared	$ 0.5	$ 0.5
American Depositary Shares [Member]
Retained Earnings Adjustments [Line Items]
ADSs repurchased during period, shares																1,627	556
ADSs repurchased during period, cost																$ 128,840	$ 50,011
Average purchase price per ADS																$ 79.18	$ 89.87
American Depositary Shares [Member] \| Maximum
Retained Earnings Adjustments [Line Items]
Repurchase of shares																		$ 200,000

Commitments And Contingencies - Additional Information (Detail) - USD ($) $ in Thousands			12 Months Ended
	Jun. 02, 2023	Feb. 18, 2021	Dec. 31, 2023	Oct. 05, 2023
Commitments and Contingencies Disclosure [Line Items]
Litigation Settlement, Amount Awarded from Other Party		$ 5,322
Loss Contingency, Estimated Recovery from Third Party			Office Building Construction On February 18, 2021, the Company won a bid with a third-party to build an office building in Taipei and entered into a property development agreement in May 2021, at which time it delivered a US$5,322 thousand performance bond secured by a certificate of deposit. Based on the terms of the property development agreement, the Company is required to complete construction within three years after the construction license is approved. As of the date of this annual report, the government has yet to approve the construction license required for the project. Litigation On June 2, 2023, the Company was named as a defendant in a patent infringement lawsuit which was filed by Unification Technologies LLC in the United States District Court for the Eastern District of Texas, Marshall Divisions. After the Company filed an inter partes review petition to invalidate one of the asserted patents on December 18, 2023, the Company reached a mutually agreed settlement with Unification Technologies LLC., which provides for payment by the Company is not expected to a material adverse effect on our business, results of operations, financial position or cash flow. The terms and conditions of the settlement are confidential under this agreement and subject to a nondisclosure obligation.On August 10, 2023, a customer of the Company’s subsidiary, Bigtera (Beijing) Ltd., filed a lawsuit in Beijing Chaoyang District Court against Bigtera (Beijing) Ltd., asserting that Bigtera (Beijing) Ltd. is in breach of its two purchase contracts with the said customer due to ceasing its operation. Beijing Chaoyang District Court accepted this case, but no court date has been scheduled so far. The ultimate outcome cannot be reasonably estimated at the current stage. On October 5, 2023, we filed a claim in the SIAC against MaxLinear for breaching the Merger Agreement. In the arbitration, we are seeking payment of the termination fee of US$160 million, together with further substantial damages, interests, and costs. However, in the event that an award is handed down in favor of the Company there is a risk that it will not be able to collect the award due to MaxLinear’s financial condition. In addition, there is a risk that if the Company does not prevail on some or all of its claims, there is a risk that it can be required to pay some or all of MaxLinear’s legal fees and costs. The arbitration tribunal has been constituted, a procedural timetable has been issued and a hearing has been fixed for October 2025. Under the SIAC Arbitration Rules, all matters relating to the proceeding are confidential.On November 20, 2023, MaxLinear filed its defense to the aforementioned claims, asserting that the Company breached the Merger Agreement because its business allegedly sustained a material adverse effect and it failed to operate its business in the ordinary course. MaxLinear also asserted a claim for fraud, alleging that the projections that it was provided prior to entering into the Merger Agreement were inflated. MaxLinear seeks damages in an unspecified amount. The Company believes that the claims are meritless. The ultimate outcome cannot be reasonably estimated at the current stage.
Loss Contingency, Domicile of Litigation	United States District Court for the Eastern District of Texas, Marshall Divisions
Loss Contingency, Lawsuit Filing Date			June 2, 2023
Breach Of Purchase Contract [Member]
Commitments and Contingencies Disclosure [Line Items]
Loss contingency, termination fee receivable				$ 160,000

Long-Term Investments - Equity Investments with Carrying Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Schedule of Equity and Cost Investments [Line Items]
Long-term investments	$ 17,116	$ 9,267
Investment, Type [Extensible Enumeration]	Equity Securities [Member]	Equity Securities [Member]
Equity Securities [Member]
Schedule of Equity and Cost Investments [Line Items]
Long-term investments	$ 6,500	$ 6,500
Cashido Corp. (Cashido)
Schedule of Equity and Cost Investments [Line Items]
Equity Investments Percentage of Ownership	0.60%	0.60%
Vastview Technology, Corp. (Vastview)
Schedule of Equity and Cost Investments [Line Items]
Equity Investments Percentage of Ownership	2.90%	2.90%
BIWIN Storage Technology Corp.(BIWIN) \| Equity Securities [Member]
Schedule of Equity and Cost Investments [Line Items]
Long-term investments	$ 10,616	$ 2,767
Equity Investments Percentage of Ownership	0.30%	0.30%
Kinara, Inc (Kinara)
Schedule of Equity and Cost Investments [Line Items]
Long-term investments	$ 6,500	$ 6,500
Equity Investments Percentage of Ownership	14.10%	14.10%

- Definition

Indicates type of investment. Includes, but is not limited to, common stock, preferred stock, convertible security, fixed income security, government security, option purchased, warrant, loan participation and assignment, commercial paper, bankers' acceptance, certificates of deposit, short-term security, repurchase agreement, and other investment company.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480524/946-210-50-6

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480524/946-210-50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.12-12A(Column A)(Footnote 2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480032/946-320-S99-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Name Accounting Standards Codification
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-Paragraph 6
-Subparagraph (SX 210.12-14(Column A)(Footnote 2))
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Name Accounting Standards Codification
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-URI https://asc.fasb.org//1943274/2147480032/946-320-S99-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 1
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-URI https://asc.fasb.org//1943274/2147480032/946-320-S99-3

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Paragraph 6
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (SX 210.12-12A(Column C)(Footnote 4))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480032/946-320-S99-2

+ Details

Segment Information - Additional Information (Detail)	12 Months Ended
Segment Information - Additional Information (Detail)	Dec. 31, 2023 Segment
Segment Reporting [Abstract]
Reportable segment	1

Property And Equipment - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Oct. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Sep. 30, 2018
Property, Plant and Equipment [Line Items]
Net carrying value of leased properties			$ 617
Annual lease and rental income from operating lease		$ 36	44	$ 44
Gain loss on disposition of assets	$ 594	(230)	0	$ 0
Shanghai Property [Member]
Property, Plant and Equipment [Line Items]
Net carrying value of leased properties		3,154	3,284
Annual lease and rental income from operating lease		$ 151	$ 157
Term of Contract		3 years
Land \| Taiwan
Property, Plant and Equipment [Line Items]
Total consideration					$ 58,931

Components of Inventories (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Inventory Disclosure [Abstract]
Finished goods	$ 61,336	$ 98,307
Work in process	86,930	111,530
Raw materials	68,684	78,127
Inventory, Net	$ 216,950	$ 287,964

Summary of Major Jurisdictions and Tax Year Subject to Examination Tax Authorities (Detail)	12 Months Ended
	Dec. 31, 2023
China
Income Tax Examination [Line Items]
Years Subject to Income Tax Examination	2020 and onward
HONG KONG
Income Tax Examination [Line Items]
Years Subject to Income Tax Examination	2020 and onward
Taiwan
Income Tax Examination [Line Items]
Years Subject to Income Tax Examination	2018 and onward
United States
Income Tax Examination [Line Items]
Years Subject to Income Tax Examination	2018 onward

Details of Cash, Cash Equivalents, and Restricted Cash (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash and Cash Equivalents [Abstract]
Cash and deposits in bank	$ 46,479	$ 70,787
Time deposits	235,570	143,267
Repurchase agreements	32,253	18,125
Total cash and cash equivalents	314,302	232,179
Restricted cash	54,688	54,876
Total cash ,cash equivalents, and restricted cash	$ 368,990	$ 287,055	$ 415,523	$ 369,211

Pension Plan (Tables)

12 Months Ended

Dec. 31, 2023

Retirement Benefits [Abstract]

Changes in Benefits Obligation and Plan Assets and Reconciliation of Funded Status

The changes in benefits obligation and plan assets and the reconciliation of funded status are as follows:


	December 31
	2021			2022			2023
	US$			US$			US$
Change in benefit obligation
Projected benefit obligation at beginning of year		1,716			1,803			244
Service cost		35			13			19
Interest cost		20			14			8
Actuarial loss (gain)		142			(205	)		(252	)
Benefits paid		(110	)		(1,236	)		—
Settlement		—			(145	)		—

Projected benefit obligation at end of year		1,803			244			19

Change in plan assets
Fair value of plan assets at beginning of year		1,551			1,639			552
Actual return on plan assets		48			120			37
Employer contributions		70			50			—
Benefits paid		(30	)		(1,257	)		—

Fair value of plan assets at end of year		1,639			552			589

Funded status recognized as an other (liability) asset		(164	)		308			570

Amounts Recognized in Accumulated Other Comprehensive Income

Amounts recognized in accumulated other comprehensive income consist of the following:


	Year Ended December 31
	2021		2022		2023
	US$		US$		US$
Net loss		718		1,322		1,070

Total recognized in accumulated other comprehensive income		718		1,322		1,070

Components of Net Periodic Benefit Cost

The components of net periodic benefit cost are as follows:


	Year Ended December 31
	2021			2022			2023
	US$			US$			US$
Service cost		35			13			19
Interest cost		20			14			8
Projected return o n p lan assets		(33	)		(30	)		(17	)
Amortization of unrecognized net transition obligation and unrecognized net actuarial gain		34			35			24
Curtailment or settlement loss		—			156			—

Net periodic benefit cost		56			188			34

Other Changes in Plan Assets and Benefit Obligation Recognized in Other Comprehensive Loss (Income)

Other changes in plan assets and benefit obligation recognized in other comprehensive loss (income):


	2021			2022		2023
	US$			US$		US$
Recognize the decrease in net gain (loss)		(36	)		604		(252	)

Total recognized in other comprehensive loss (income)		(36	)		604		(252	)

Expected Benefit Payments

Expected benefit payments:


	US$
2024		17
2025		5
2026		5
2027		5
2028		5
2029 and thereafter		101

Actuarial Assumptions to Determine Benefit Obligations

The actuarial assumptions to determine the benefit obligations are as follows:


	2021			2022			2023
Weighted-average assumptions used to determine benefit obligations:
Discount rate		0.75	%		1.75	%		1.41	%
Rate of compensation increase		4.00	%		4.50	%		4.00	%
Weighted-average assumptions used to determine net projected benefit cost:
Discount rate		0.75	%		1.75	%		1.41	%
Expected long-term return on plan assets		2.00	%		3.00	%		3.00	%
Rate of compensation increase		4.00	%		4.50	%		4.00	%

Long-term Investment - Additional Information (Detail) - USD ($) $ in Thousands		1 Months Ended			12 Months Ended
	Mar. 31, 2020	Jul. 31, 2021	May 31, 2021	Jun. 30, 2018	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Equity and Cost Investments [Line Items]
Unrealized holding gain on investment					$ 8,002	$ 896	$ 0
Simple Agreement For Future Equity [Member]
Schedule of Equity and Cost Investments [Line Items]
Invested in common stock	$ 2,000		$ 1,500
Kinara [Member]
Schedule of Equity and Cost Investments [Line Items]
Invested in common stock				$ 3,000
BIWIN Storage Technology Corp.(BIWIN) [Member]
Schedule of Equity and Cost Investments [Line Items]
Invested in common stock		$ 2,041

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current Assets
Cash and cash equivalents	$ 314,302	$ 232,179
Accounts receivable, net	194,701	206,105
Inventories	216,950	287,964
Restricted assets-current	49,656	49,490
Prepaid expenses and other current assets	17,636	12,184
Total current assets	793,245	787,922
Long-term investments	17,116	9,267
Property and equipment, net	167,417	139,434
Deferred income tax assets, net	8,456	8,884
Operating lease assets	14,134	8,149
Other assets	7,593	7,594
Total assets	1,007,961	961,250
Current Liabilities
Notes and accounts payable	55,586	36,023
Income tax payable	7,544	42,114
Refund liabilities	3,329	6,471
Accrued expenses and other current liabilities	146,351	99,260
Total current liabilities	212,810	183,868
Other long-term liabilities	60,455	44,781
Total liabilities	273,265	228,649
Commitments and Contingencies (Note 16)
Shareholders' Equity
Ordinary Shares at US$0.01 par value per share Authorized: 500,000 thousand shares Issued and outstanding: 132,216 thousand shares in 2022 and 133,676 thousand shares in 2023	1,337	1,322
Additional paid-in capital	321,050	303,564
Accumulated other comprehensive income	1,153	2,595
Retained earnings	411,156	425,120
Total shareholders' equity	734,696	732,601
Total liabilities and shareholders' equity	$ 1,007,961	$ 961,250