Summary of Significant Accounting Policies - Schedule of Restricted Cash (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restricted Cash and Cash Equivalents Items [Line Items]
Other assets	$ 1,902,000	$ 364,000	$ 364,000	$ 155,000
Debt covenant, cash requirement percentage	125.00%
Debt covenant, minimum consolidated cash amount	$ 2,500,000
Debt covenant, amount to be maintained	25,000,000.0
Letter of credit security: Cambridge lease | Letter of Credit
Restricted Cash and Cash Equivalents Items [Line Items]
Other assets	264,000	264,000
Letter of credit security: Waltham lease | Letter of Credit
Restricted Cash and Cash Equivalents Items [Line Items]
Other assets	250,000	0
Letter of credit security: Vienna Austria lease | Letter of Credit
Restricted Cash and Cash Equivalents Items [Line Items]
Other assets	94,000	0
Letter of credit security: Allston lease | Letter of Credit
Restricted Cash and Cash Equivalents Items [Line Items]
Other assets	1,144,000	0
Corporate credit card collateral
Restricted Cash and Cash Equivalents Items [Line Items]
Other assets	$ 150,000	$ 100,000