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Pension Plan - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accumulated benefit obligation	$ 1,008	$ 939	$ 3,864
Estimated amortization of net gain from accumulated other comprehensive income into net periodic benefit cost over the next fiscal year	33
SMI Taiwan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions and Recognized Pension Costs under Labor Pension Act	$ 2,109	$ 1,783	$ 1,682
Contributions Based on Percentage Employee Salaries under Labor Standards Law	2.00%
The contribution under defined benefit plans	$ 61
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%

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Defined Benefit Plan, Contributions, Percent of Compensation

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Percentage of Pension Payment to Employee Benefits

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Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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Amount included in accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan expected to be recognized in net periodic benefit (cost) credit for fiscal year following most recent annual statement of financial position.

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Amount of contribution expected to be received by defined benefit plan from employer in next fiscal year following current fiscal year.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
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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.

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Amount of cash outflow for pension benefit. Includes, but is not limited to, employer contribution to fund plan asset and payment to retiree. Excludes other postretirement benefit.

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-Publisher FASB
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-Topic 230
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