Net Sales by Product (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Sales Information [Line Items]
Net product sales	$ 41,092	$ 39,443	$ 123,549	$ 114,304
BELBUCA
Sales Information [Line Items]
Net product sales	$ 36,930	$ 34,758	$ 109,836	$ 100,572
BELBUCA | Revenue Benchmark | Product Concentration Risk
Sales Information [Line Items]
Percent of net product sales	90.00%	90.00%	90.00%	89.00%
Symproic
Sales Information [Line Items]
Net product sales	$ 4,142	$ 3,453	$ 12,562	$ 11,046
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	$ 574	$ 0	$ 1,328
BUNAVAIL | Revenue Benchmark | Product Concentration Risk
Sales Information [Line Items]
Percent of net product sales	0.00%	1.00%	0.00%	1.00%
Product sales, net
Sales Information [Line Items]
Net product sales	$ 41,072	$ 38,785	$ 122,398	$ 112,946