Income Taxes - Schedule of Effective Income Tax Amount Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
U.S. federal tax at statutory rate									$ (934)	$ 17	$ (2,958)
U.S. state income taxes									(65)	2,539	(708)
Non-deductible expense (benefit)									5,899	14,485	(5,673)
Research and development credit									(860)	(339)	(402)
Stock-based compensation									(16,619)	(11,360)	(14,622)
Impact of 2017 Tax Act									0	0	25,952
Other									(129)	106	2
Change in valuation allowance									12,812	(5,148)	(1,323)
Total provision for income taxes	$ 74	$ 50	$ 29	$ (49)	$ 150	$ 41	$ 64	$ 45	$ 104	$ 300	$ 268