SEGMENT REPORTING - Revenue (Details) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2024 USD ($)	Mar. 31, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) segment	Sep. 30, 2023 USD ($)
Segment reporting
Number of operating segments | segment				2
Total net revenues	$ 148,332		$ 131,829	$ 423,802	$ 355,162
Depreciation and amortization	15,748		15,207	45,131	44,597
Selling, general and administrative expenses	79,075		42,007	179,917	117,235
Operating (loss) income	(20,519)		17,948	4,962	40,245
Unrealized gain on investment in equity securities	1,355		0	8,298	0
Interest expense, net	(2,331)		(6,398)	(11,587)	(21,194)
Other expense, net	(2,535)		(39)	(2,655)	(126)
(Loss) Income Before Income Tax (Benefit) Expense	(31,498)		11,511	(8,450)	18,925
Gain on sale of building	0	$ 5,300	0	5,347	0
Loss on extinguishment of debt	7,468		0	7,468	0
Operating Segments | Generics, Established Brands, and Other
Segment reporting
Total net revenues	91,906		102,095	281,246	284,794
EBITDA	33,588		41,234	110,528	120,070
Operating Segments | Rare Disease
Segment reporting
Total net revenues	56,426		29,734	142,556	70,368
EBITDA	6,626		4,044	14,826	6,937
Corporate, Non-Segment
Segment reporting
Depreciation and amortization	(15,748)		(15,207)	(45,131)	(44,597)
Selling, general and administrative expenses	(44,985)		(12,123)	(75,261)	(42,165)
Operating (loss) income	(20,519)		17,948	4,962	40,245
Unrealized gain on investment in equity securities	1,355		0	8,298	0
Interest expense, net	(2,331)		(6,398)	(11,587)	(21,194)
Other expense, net	$ (10,003)		$ (39)	$ (10,123)	$ (126)