SEGMENT RESULTS - Schedule of Disaggregation of Revenues (Details) - USD ($)	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	$ 772,028,000				$ 634,860,000		$ 2,203,777,000	$ 2,142,853,000
Product line revenue reporting threshold	25,000,000	$ 25,000,000	$ 25,000,000	$ 25,000,000	25,000,000	$ 25,000,000
Branded Pharmaceuticals
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	230,977,000				223,682,000		665,652,000	557,276,000
Branded Pharmaceuticals | Specialty Products
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	161,917,000				140,120,000		472,338,000	343,161,000
Branded Pharmaceuticals | XIAFLEX®
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	105,509,000				88,167,000		312,266,000	211,022,000
Branded Pharmaceuticals | SUPPRELIN® LA
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	30,069,000				28,229,000		85,665,000	63,344,000
Branded Pharmaceuticals | Other Specialty
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	26,339,000				23,724,000		74,407,000	68,795,000
Branded Pharmaceuticals | Established Products
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	69,060,000				83,562,000		193,314,000	214,115,000
Branded Pharmaceuticals | PERCOCET®
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	26,914,000				27,508,000		78,695,000	82,789,000
Branded Pharmaceuticals | TESTOPEL®
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	11,686,000				18,068,000		32,314,000	26,877,000
Branded Pharmaceuticals | Other Established
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	30,460,000				37,986,000		82,305,000	104,449,000
Sterile Injectables
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	343,653,000				251,393,000		946,998,000	906,997,000
Sterile Injectables | VASOSTRICT®
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	255,697,000				155,412,000		676,764,000	572,530,000
Sterile Injectables | ADRENALIN®
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	28,722,000				30,662,000		88,136,000	120,335,000
Sterile Injectables | Other Sterile Injectables
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	59,234,000				65,319,000		182,098,000	214,132,000
Generic Pharmaceuticals
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	174,306,000				135,508,000		522,451,000	602,670,000
International Pharmaceuticals
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	$ 23,092,000				$ 24,277,000		$ 68,676,000	$ 75,910,000
International Pharmaceuticals | Revenue from Contract with Customer Benchmark | Product Concentration Risk | Maximum
Disaggregation of Revenue [Line Items]
Concentration risk, percentage							5.00%	5.00%