Collaborative arrangements - Changes in Balances of Company's Receivables and Contract Liabilities (Detail) - Bristol-Myers Squibb $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Receivables
Balance at beginning of period	$ 400
Additions	12,400
Deductions	(12,400)
Balance at end of period	400
Contract liabilities:
Balance at beginning of period	18,265
Additions	200,000
Deductions	(191,683)
Balance at end of period	$ 26,582