Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets
Net operating losses	$ 79,035	$ 56,555
Tax credit carryforward	11,152	6,709
Non qualifying stock options	9,150	7,861
Deferred rent	11,755	1,925
Other	3,598	2,598
Total deferred tax assets	114,690	75,648
Valuation allowance	(100,906)	(70,722)
Deferred tax assets, net of valuation allowance	13,784	4,926
Deferred tax liabilities
Tangible and intangible assets	(13,784)	(4,926)
Net deferred taxes	$ 0	$ 0