Summary of Significant Accounting Policies - Significant Accounting Policies (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
	Jan. 01, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Mar. 05, 2020	Jan. 31, 2019
Research and development incentive income and receivable
Research and development expenses reimbursed (as a percent)		43.50%		43.50%		43.50%
Adjustment to increase Australian research and development incentive income		$ 150
Research and development incentive income and receivable
Balance at the beginning of the period	$ 836			$ 185	$ 836	$ 836
Australian research and development incentive income, net		228	$ (7)	343	129	132
Cash received for eligible expenses				(331)		(757)
Foreign currency translation				12		(26)
Balance at the end of the period		209		209		185
Deferred Offering Costs
Deferred Offering Costs Noncurrent		379		379		831
Other Assets
Deposits with service providers that are to be applied to future payments		$ 941		941		$ 1,099
Warrant liability reclassified to equity	$ 3,448				3,448
Dividend attributable to down round feature of warrants				$ 303	359
Incremental borrowing rate		8.00%		8.00%
2019 Public Offering
Other Assets
Exercise price of warrant		$ 1.75		$ 1.75				$ 6.085
Dividend attributable to down round feature of warrants					$ 359
January 2020 Private Placement
Other Assets
Exercise price of warrant		$ 1.055		$ 1.055			$ 2.11	$ 1.75
Dividend attributable to down round feature of warrants				$ 303