Royalty and other revenue - Additional Information (Detail) - Royalty and other revenue - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
License And Royalty Revenue [Line Items]
Revenue	$ 1,534		$ 3,499	$ 7,379	$ 17,086
Juno Therapeutics
License And Royalty Revenue [Line Items]
Revenue		$ 2,500