Summary of Significant Accounting Policies - Significant Accounting Policies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Accounting policies:
Eligible for reimbursement (as a percent of R&D expense)	43.50%	43.50%
Research and development incentive income and receivable
Balance at the beginning of the period	$ 836	$ 1,744
Australian research and development incentives	132	756
Cash received eligible overseas research and development expenses		(740)
Cash received for eligible expenses	(757)	(793)
Foreign currency translation	(26)	(131)
Balance at the end of the period	185	836
Other Assets
Deposits	1,099	1,380
Deferred offering costs	831	162
Uncertain tax positions	0	0
Service agreements
Other Assets
Deposits	$ 1,099	$ 1,380
Office equipment
Other Assets
Useful life (in years)	5 years
Computer equipment
Other Assets
Useful life (in years)	3 years
Lab equipment
Other Assets
Useful life (in years)	5 years
Furnitures and fixtures
Other Assets
Useful life (in years)	5 years