Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Net operating loss carryforwards	$ 33,008	$ 37,417
Tax credit carryforwards	17,185	12,751
Deferred revenue	0	26,739
Deferred lease incentive	0	103
Deferred rent	0	476
Operating lease liability	5,407
Intangibles	519	552
Accrued expenses and other	1,358	1,091
Unrealized loss on available-for-sale securities	17	39
Stock-based compensation	3,376	2,119
Total deferred tax assets	60,870	81,287
Less: valuation allowance	(43,219)	(55,348)
Net deferred tax assets	17,651	25,939
Deferred tax liabilities:
Section 481(a) method change	(12,827)	(25,653)
Operating lease right-of-use asset	(4,812)
Depreciation	(12)	(286)
Total deferred tax liabilities	(17,651)	(25,939)
Net deferred taxes	$ 0	$ 0