Significant Accounting Policies - Additional Information (Details)	3 Months Ended
	Mar. 31, 2020 USD ($) Segment	Jan. 01, 2020 USD ($)	Dec. 31, 2019 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Cash cash equivalents and marketable securities	$ 341,100,000		$ 367,800,000
Restricted cash	$ 600,000		600,000
Number of operating segment | Segment	1
Operating lease right-of-use asset	$ 6,624,000	$ 6,800,000	$ 0
Operating lease liability	15,135,000	15,600,000
Deferred rent		8,800,000
Revenue recognized from performance obligations satisfied in previous periods	0
ASU 842
Summary Of Significant Accounting Policies [Line Items]
Operating lease right-of-use asset		6,800,000
Operating lease liability		15,600,000
Deferred rent		$ 8,800,000
ASC 606 | Adjustments
Summary Of Significant Accounting Policies [Line Items]
Cumulative adjustment to decrease accumulated deficit and deferred revenue	$ 400,000