Collaborative arrangements - Changes in Balances of Company's Receivables and Contract Liabilities (Detail) - Bristol-Myers Squibb $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Receivables
Balance at beginning of period	$ 6,528
Additions	11,250
Deductions	(17,378)
Balance at end of period	400
Contract liabilities:
Balance at beginning of period	34,939
Additions	10,000
Deductions	(26,674)
Balance at end of period	$ 18,265