Income Taxes - Income Tax Provision (Benefit) Differs from Computed Using Federal Statutory Rate Applied to Income before Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Tax provision computed at the federal statutory rate	$ (30,365)	$ (26,854)	$ (42,614)
State tax, net of federal benefit	(4,126)	(5,077)	(2,207)
Research and development expense tax credits	(2,526)	(4,884)	(1,176)
Change in uncertain tax benefit reserve	0	0	(561)
Change in tax credit carryforwards	81	(3,056)	386
Officers compensation	1,506	600	(9,292)
Stock based compensation	(230)	(12,610)	(2,734)
Permanent items and other	267	(116)	1,450
Tax differential on foreign earnings	(31)	(32)	33
Change in tax rate	1,126	(1,329)	37,768
Refundable alternative minimum tax credit	0	0	(1,336)
Change in prior year deferred taxes	1,170	6,595	(1,218)
Valuation allowance	23,920	44,862	(440)
Total income tax benefit	$ (9,208)	$ (1,901)	$ (21,941)