Restricted cash - Schedule of Collateralized Bank Account of Financial Institution (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt and Equity Securities, FV-NI [Line Items]
Total restricted cash	$ 45,500	$ 56,023
50 Binney Street lease
Debt and Equity Securities, FV-NI [Line Items]
Total restricted cash	40,072	40,072
Assembly Row lease
Debt and Equity Securities, FV-NI [Line Items]
Total restricted cash	2,753	0
60 Binney Street lease
Debt and Equity Securities, FV-NI [Line Items]
Total restricted cash	0	13,763
Other
Debt and Equity Securities, FV-NI [Line Items]
Total restricted cash	$ 2,675	$ 2,188