SEGMENT RESULTS - Schedule of Disaggregation of Revenues (Details) - USD ($)	3 Months Ended						6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	$ 713,830,000				$ 687,588,000		$ 1,431,749,000	$ 1,507,993,000
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	228,040,000				129,521,000		434,675,000	333,594,000
Branded Pharmaceuticals | Specialty Products
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	167,091,000				68,744,000		310,421,000	203,041,000
Branded Pharmaceuticals | XIAFLEX®
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	111,487,000				33,783,000		206,757,000	122,855,000
Branded Pharmaceuticals | SUPPRELIN® LA
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	27,568,000				15,395,000		55,596,000	35,115,000
Branded Pharmaceuticals | Other Specialty
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	28,036,000				19,566,000		48,068,000	45,071,000
Branded Pharmaceuticals | Established Products
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	60,949,000				60,777,000		124,254,000	130,553,000
Branded Pharmaceuticals | PERCOCET®
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	26,156,000				27,578,000		51,781,000	55,281,000
Branded Pharmaceuticals | TESTOPEL®
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	9,439,000				617,000		20,628,000	8,809,000
Branded Pharmaceuticals | Other Established
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	25,354,000				32,582,000		51,845,000	66,463,000
Sterile Injectables
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	294,600,000				319,214,000		603,345,000	655,604,000
Sterile Injectables | VASOSTRICT®
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	197,121,000				214,214,000		421,067,000	417,118,000
Sterile Injectables | ADRENALIN®
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	29,977,000				33,161,000		59,414,000	89,673,000
Sterile Injectables | Other Sterile Injectables
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	67,502,000				71,839,000		122,864,000	148,813,000
Generic Pharmaceuticals
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	167,272,000				215,879,000		348,145,000	467,162,000
International Pharmaceuticals
Disaggregation of Revenue [Line Items]
TOTAL REVENUES, NET	$ 23,918,000				$ 22,974,000		$ 45,584,000	$ 51,633,000
International Pharmaceuticals | Revenue from Contract with Customer Benchmark | Product Concentration Risk | Maximum
Disaggregation of Revenue [Line Items]
Concentration risk, percentage							5.00%	5.00%