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Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
Corporate income tax rate		20.00%	20.00%	17.00%
Change in tax rate for undistributed portion of earnings		5.00%	5.00%	10.00%
Unrecognized tax benefits that if recognized would affect the effective tax rate	$ 0	$ 0	$ 0
Unrecognized tax benefits that if recognized would be offset by a valuation allowance	0	0	0
Unrecognized tax benefits, income tax penalties and interest expense	$ 0	$ 0	$ 0
Taiwan | Undistributed Foreign Earnings
Income Tax Contingency [Line Items]
Tax loss carryforward period	10 years

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- Definition

Change in tax rate for undistributed portion of earnings, percentage.

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- Definition

Corporate income tax rate.

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- Definition

Tax loss carryforward period.

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- Definition

Unrecognized tax benefits if recognized would impact valuation allowance.

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- Definition

Amount of expense for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32718-109319

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- Definition

The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=SL6600010-109319

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