REVENUE - Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Contract assets:
Additions			$ 60,705
Deletions			(21,426)
Contract asset, End of Period	$ 39,279		39,279
Net revenues	63,274	$ 100,457	191,678	$ 190,904
Accrued royalties	3,672		3,672						$ 17,370
Prepaid and other current assets
Contract assets:
Contract asset, End of Period	9,900		9,900
Other long-term assets
Contract assets:
Contract asset, End of Period	24,400		24,400
Collegium
Contract assets:
Additions			55,705
Deletions			(21,426)
Contract asset, End of Period	34,279		34,279
Grunenthal | Maximum | Forecast
Contract assets:
Royalty obligation					$ 8,800	$ 8,800	$ 8,800	$ 8,800
Ironwood Pharmaceuticals, Inc.
Contract assets:
Additions			5
Contract asset, End of Period	5		5
NUCYNTA products | Grunenthal | Minimum | Forecast
Contract assets:
Royalty obligation					34,000	34,000	34,000	34,000
Net revenues					180,000	180,000	180,000	180,000
NUCYNTA products | Grunenthal | Maximum
Contract assets:
Net revenues					243,000	243,000	243,000	243,000
Collegium | NUCYNTA products | Grunenthal | Minimum | Forecast
Contract assets:
Royalty obligation					$ 34,000	$ 34,000	$ 34,000	$ 34,000
Product sales, net
Contract assets:
Net revenues	$ 26,838	$ 100,232	$ 71,192	$ 190,517