Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 31, 2001
Income Tax [Line Items]
Statutory tax rate	34.00%		21.00%
Net deferred tax assets	$ 68	$ 3,114	$ 1,807
Valuation allowance, deferred tax assets, increase (decrease)	9,900	(3,300)	(14,900)
Unrecognized tax benefits	8,740	5,887	2,517	$ 2,050
Unrecognized tax benefits, recognized penalties and interest	300	400	400
Unrecognized tax benefits, income tax penalties and interest accrued	1,600	1,300
Tax Cuts and Jobs Act, decrease in deferred tax liability			16,100
Tax Cuts and Jobs Act, provisional income tax expense (benefit)			$ 1,100
Non-current Income Taxes Payable
Income Tax [Line Items]
Unrecognized tax benefits	3,500	3,500
Deferred Tax Assets, Noncurrent
Income Tax [Line Items]
Unrecognized tax benefits	5,300	$ 2,400
U.S.
Income Tax [Line Items]
Operating loss carryforwards	95,800
U.S. | Research and Development Credit
Income Tax [Line Items]
Tax credit carryforward	5,900
State
Income Tax [Line Items]
Operating loss carryforwards	14,000
State | Research and Development Credit
Income Tax [Line Items]
Tax credit carryforward	$ 13
Change in ownership event one
Income Tax [Line Items]
Tax credit carryforward, limitation					$ 17
Change in ownership event two
Income Tax [Line Items]
Tax credit carryforward, limitation					52
Change in ownership event three
Income Tax [Line Items]
Tax credit carryforward, limitation					$ 459
China | Foreign Tax Authority [Member]
Income Tax [Line Items]
Statutory tax rate	25.00%
Finland | Foreign Tax Authority [Member]
Income Tax [Line Items]
Statutory tax rate	20.00%