Summary of Significant Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) reporting_unit	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Mar. 31, 2019 USD ($)	Mar. 13, 2019 USD ($)	Jan. 01, 2019 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of reporting units | reporting_unit	1
Fair value of warrants				$ 288,000	$ 5,200,000
Currency translation adjustments	$ (119,000)	$ 0	$ 0
Operating lease, liability	2,816,000
Right-of-use assets	$ 1,959,000
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, liability						$ 2,500,000
Right-of-use assets						$ 2,000,000.0
Arsanis
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Fair value of warrants					$ 0