Income Taxes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Non-U.S. income included in income (loss) before tax	$ 12,100,000	$ 2,800,000	$ 6,500,000
Current:
State	15,000	27,000	5,000
Foreign	2,016,000	535,000	933,000
Total current	2,031,000	562,000	938,000
Total provision for income taxes	$ 2,031,000	$ 562,000	$ 938,000
Reconciliation of effective income tax rates and U.S. statutory federal income tax rate [Abstract]
Statutory federal income tax rate (as a percent)	21.00%	21.00%	21.00%
State income taxes, net of federal tax benefits (as a percent)	0.20%	(2.10%)
Valuation allowance (as a percent)	0.80%	(173.00%)	(2.60%)
Stock-based compensation (as a percent)	(1.90%)	(21.80%)	0.30%
Foreign tax rate differential (as a percent)	2.10%	137.70%	(11.40%)
Foreign income tax incentive (as a percent)	(3.80%)	32.20%	(2.90%)
Foreign tax incentives (as a percent)	7.8		2.6
Tax effect in equity method loss or gain from unconsolidated affiliates (as a percent)	1.10%	(47.80%)	3.20%
Foreign-derived intangible income (as percent)			(2.40%)
Others (as a percent)	1.40%	(1.00%)	0.10%
Effective tax rate (as a percent)	28.70%	(54.80%)	7.90%
Deferred tax assets:
Net operating loss carryforwards	$ 14,328,000	$ 14,979,000
Accruals, reserves and other	3,756,000	3,011,000
Credit carryforwards	1,685,000	1,685,000
Operating lease liability	178,000	209,000
Gross deferred tax assets	19,947,000	19,884,000
Valuation allowance	(19,798,000)	(19,691,000)
Total deferred tax assets	149,000	193,000
Deferred tax liabilities:
Operating lease right-of-use assets	(149,000)	(193,000)
Increase (decrease) in valuation allowance	$ 100,000	200,000	$ (2,600,000)
Realized benefits of tax rate reduction (as a percent)	10.00%
Unrecognized tax benefit would favorably impact the effective tax rate in future periods if recognized	$ 14,600,000	14,600,000
Domestic Tax Authority
Deferred tax liabilities:
Operating loss carryforwards	57,000,000.0
Tax credit carryforwards	$ 800,000
Foreign Tax Authority
Deferred tax liabilities:
EIT income tax rate (as a percent)	25.00%
Preferential tax rate (as a percent)	15.00%
Benefit from foreign tax rate	$ 973,000	$ 211,000	$ 764,000