Income Taxes - Schedule of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Federal, state and foreign net operating loss carryforwards	$ 237,708	$ 186,963
Capitalized research and development	666	486
Accrued expenses	5,895	2,498
Research and development credits	5,343	5,343
Amortization	2,718	2,949
Lease liability	2,291	2,534
Stock-based compensation	10,212	7,878
Other, net	2,523	2,690
Total deferred tax assets	267,356	211,341
Less: valuation allowance	(231,335)	(176,594)
Total deferred tax assets, net of valuation allowance	36,021	34,747
Operating lease right-of-use asset	(1,423)	(1,585)
IPR&D	(18,573)	(15,857)
Discount on Notes	(16,025)	(17,305)
Total deferred tax liabilities	(36,021)	(34,747)
Total net deferred tax liabilities	$ 0	$ 0