Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Summary Of Significant Accounting Policies [Line Items]
Operating lease right-of-use asset	$ 2,627		$ 2,627
Operating Lease, Liability	5,904		5,904
ASU 2016-02
Summary Of Significant Accounting Policies [Line Items]
Operating lease right-of-use asset	2,800		2,800
Operating Lease, Liability	6,200		6,200
Deferred rent	3,400		3,400
Australian Research and Development Tax Incentive | Australian Taxation Office
Summary Of Significant Accounting Policies [Line Items]
Tax incentive receivable, reductions to research and development expense	$ 200	$ 600	$ 300	$ 900