Net Sales by Product (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Sales Information [Line Items]
Net product sales	$ 41,439	$ 36,582	$ 82,458	$ 74,861
BELBUCA
Sales Information [Line Items]
Net product sales	$ 36,504	$ 32,344	$ 72,906	$ 65,813
BELBUCA | Revenue Benchmark | Product Concentration Risk
Sales Information [Line Items]
Percent of net product sales	90.00%	89.00%	90.00%	89.00%
Symproic
Sales Information [Line Items]
Net product sales	$ 4,019	$ 3,413	$ 8,420	$ 7,593
Symproic | Revenue Benchmark | Product Concentration Risk
Sales Information [Line Items]
Percent of net product sales	10.00%	9.00%	10.00%	10.00%
BUNAVAIL
Sales Information [Line Items]
Net product sales	$ 0	$ 688	$ 0	$ 755
BUNAVAIL | Revenue Benchmark | Product Concentration Risk
Sales Information [Line Items]
Percent of net product sales	0.00%	2.00%	0.00%	1.00%
Product sales, net
Sales Information [Line Items]
Net product sales	$ 40,523	$ 36,445	$ 81,326	$ 74,161