Income Taxes - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) event	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Income Tax [Line Items]
Statutory tax rate	21.00%
Net deferred tax assets	$ 69	$ 68	$ 3,114
Valuation allowance, deferred tax assets, increase (decrease)	$ 8,100	9,900	(3,300)
Number of change in ownership events | event	3
Unrecognized tax benefits	$ 7,859	8,740	5,887	$ 2,517
Unrecognized tax benefits, recognized penalties and interest	500	300	$ 400
Unrecognized tax benefits, income tax penalties and interest accrued	2,100	1,600
Non-current Income Taxes Payable
Income Tax [Line Items]
Unrecognized tax benefits	3,700	3,500
Non-current Deferred Tax Assets
Income Tax [Line Items]
Unrecognized tax benefits	4,200	$ 5,300
Research and Development Credit
Income Tax [Line Items]
Tax credit carryforward	6,700
U.S.
Income Tax [Line Items]
Operating loss carryforwards	119,100
Foreign Tax Authority
Income Tax [Line Items]
Operating loss carryforwards	11,800
State
Income Tax [Line Items]
Operating loss carryforwards	16,500
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
Income Tax [Line Items]
Statutory tax rate	25.00%
Finland | Foreign Tax Authority
Income Tax [Line Items]
Statutory tax rate	20.00%