Income Taxes - Components of Company's Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Net operating loss carry forwards	$ 187,129	$ 143,045
Research and development expense tax credits	27,341	25,424
Stock based compensation	5,470	4,037
Lease obligation	783	599
Development costs	286	487
Returns and allowances	1,198	1,061
Amortization differences	1,749	1,479
Depreciation	57	4,746
Other, net	20,267	17,420
Total deferred tax assets before valuation allowance	244,280	198,298
Valuation allowance	(242,590)	(192,513)
Total deferred tax assets	1,690	5,785
Deferred tax liabilities, net:
Unrealized gains	(973)	(5,230)
Right-of-use asset	(717)	(555)
Net deferred tax liabilities	$ 0	$ 0