Income Taxes - Schedule of Significant Components Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 84,827	$ 81,406
Research and development credits	24,179	24,011
Deferred royalty obligation	36,265	30,460
Share-based compensation expense	2,497	9,581
Depreciation and amortization expense	1,044
Lease liability	136	7,127
Other	436	1,263
Total gross deferred tax assets	149,384	153,848
Depreciation and amortization		(1,612)
Right-of-use lease asset	(136)	(3,775)
Valuation allowance	$ (149,248)	$ (148,461)