Income Taxes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Non-U.S. income included in income (loss) before tax	$ 2,800,000	$ 6,500,000	$ 6,400,000
Current:
State	27,000	5,000	2,000
Foreign	535,000	933,000	790,000
Total current	562,000	938,000	792,000
Total provision for income taxes	$ 562,000	$ 938,000	$ 792,000
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%	35.00%
State income taxes, net of federal tax benefits (as a percent)	(2.10%)
Valuation allowance (as a percent)	(173.00%)	(2.60%)	(139.50%)
Rate change (as a percent)			100.80%
Stock-based compensation (as a percent)	(21.80%)	0.30%	(10.40%)
Foreign tax rate differential (as a percent)	137.70%	(11.40%)	(10.30%)
Foreign income tax incentive (as a percent)	32.20%	(2.90%)	(7.00%)
Foreign tax incentives (as a percent)		2.60%	55.60%
Section 78 gross up			11.70%
Foreign tax credit (as a percent)			(30.60%)
Tax effect in equity method loss or gain from unconsolidated affiliates (as a percent)	(47.80%)	3.20%	2.90%
Foreign-derived intangible income (as percent)		(2.40%)
Others (as a percent)	(1.00%)	0.10%	(0.90%)
Effective tax rate (as a percent)	(54.80%)	7.90%	7.30%
Deferred tax assets:
Net operating loss carryforwards	$ 14,979,000	$ 15,735,000
Accruals, reserves and other	3,011,000	2,100,000
Credit carryforwards	1,685,000	1,685,000
Operating lease liability	209,000
Gross deferred tax assets	19,884,000	19,520,000
Valuation allowance	(19,691,000)	(19,520,000)
Total deferred tax assets	193,000
Deferred tax liabilities:
Operating lease right-of-use assets	(193,000)
Increase (decrease) in valuation allowance	$ 200,000	(2,600,000)	$ (46,300,000)
Realized benefits of tax rate reduction (as a percent)	10.00%
Reconciliation of beginning and ending amount of the gross unrecognized tax benefits [Roll Forward]
Gross unrecognized tax benefits beginning balance	$ 14,557,000	14,557,000	14,557,000
Gross unrecognized tax benefits ending balance	14,557,000	14,557,000	14,557,000
Unrecognized tax benefit would favorably impact the effective tax rate in future periods if recognized	14,600,000
Domestic Tax Authority
Deferred tax liabilities:
Operating loss carryforwards	58,300,000
Tax credit carryforwards	$ 1,700,000
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	$ 211,000	$ 764,000	$ 599,000