Summary of Significant Accounting Policies - Additional Information (Details)			9 Months Ended
	Feb. 07, 2020	Jan. 01, 2020 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Reverse stock split	0.2055
Reverse stock split, description			1-for-4.8661
Operating lease liability			$ 33,314,000
Operating right-to-use asset			28,194,000
Accumulated deficit			$ (231,341,000)	$ (157,386,000)
ASU 2016-02
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date			Jan. 01, 2020
Change in accounting principle, accounting standards update, early adoption			false
Change in accounting principle, accounting standards update, adopted			true
Change in accounting principle, accounting standards update, immaterial effect			true
Operating lease liability		$ 11,500,000
Operating right-to-use asset		9,100,000
Deferred rent derecognized		$ 2,400,000
Estimated incremental borrowing rate of funds		5.00%
ASU 2016-02 | Cumulative Effect Period of Adoption Adjustment
Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit		$ 0
ASU 2018-11
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date			Jan. 01, 2020
Change in accounting principle, accounting standards update, early adoption			false
Change in accounting principle, accounting standards update, adopted			true
Change in accounting principle, accounting standards update, immaterial effect			true
ASU 2019-01
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date			Jan. 01, 2020
Change in accounting principle, accounting standards update, early adoption			false
Change in accounting principle, accounting standards update, adopted			true
Change in accounting principle, accounting standards update, immaterial effect			true
ASU 2018-07
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date			Jan. 01, 2020
Change in accounting principle, accounting standards update, early adoption			false
Change in accounting principle, accounting standards update, adopted			true
Change in accounting principle, accounting standards update, immaterial effect			true
ASU 2018-13
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date			Jan. 01, 2020
Change in accounting principle, accounting standards update, early adoption			false
Change in accounting principle, accounting standards update, adopted			true
Change in accounting principle, accounting standards update, immaterial effect			true
ASU 2018-18
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date			Jan. 01, 2020
Change in accounting principle, accounting standards update, early adoption			false
Change in accounting principle, accounting standards update, adopted			true
Change in accounting principle, accounting standards update, immaterial effect			true