Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Non-cancelable operating sublease, expiration date for initial leased space	2024-12
Non-cancelable operating sublease, expiration date for expansion space leased	2022-12
Lessee, Operating Sublease, Existence of Option to Extend [true false]	true
Lessee, operating sublease, option to extend	options to extend for the entire premises through October 2028
Operating sublease, annual increase percentage for base rent	3.00%
Lessee, operating lease, discount rate	7.00%
Weighted average remining lease term	5 years
Cash paid for operating lease liabilities	$ 1.2
Rent expense		$ 0.5