INTANGIBLE ASSETS - Additional information (Details) - USD ($)		1 Months Ended								3 Months Ended		12 Months Ended
	Apr. 30, 2016	Jul. 31, 2019	Mar. 31, 2019	Jan. 31, 2019	May 31, 2018	Apr. 30, 2018	Dec. 31, 2017	Feb. 28, 2017	May 31, 2015	Dec. 31, 2019	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
INTANGIBLE ASSETS
Amortization of Intangible Assets												$ 40,200,000	$ 31,700,000	$ 26,700,000
Payments to Acquire Intangible Assets												$ 20,914,000	5,169,000	97,624,000
Finite-Lived Intangible Asset, Useful Life												10 years
Goodwill, Impairment Loss												$ 0	0
Finite-Lived Intangible Assets, Gross										$ 307,225,000		307,225,000	288,215,000
Impairment of Intangible Assets, Finite-lived												$ 75,000	0	903,000
Acquired Finite-lived Intangible Asset, Amortization Description												we are amortizing 80% of the value of the intangible assets over the first five years of useful lives of the assets and amortizing the remaining 20% of the value of the intangible assets over the second five years of useful lives of the assets.
Pharmaceutics International, Inc and BAS ANDA LLC [Member]
INTANGIBLE ASSETS
Payments to Acquire Intangible Assets										500,000
Finite-Lived Intangible Asset, Useful Life												10 years
Appco Pharma, LLC [Member]
INTANGIBLE ASSETS
Payments to Acquire Intangible Assets		$ 80,000
Finite-Lived Intangible Asset, Useful Life											8 years
Finite-Lived Intangible Assets, Gross		80,000
Impairment of Intangible Assets, Finite-lived										75,000		$ 75,000
Inderal XL [Member]
INTANGIBLE ASSETS
Payments to Acquire Intangible Assets								$ 20,200,000
Finite-Lived Intangible Asset, Useful Life								10 years
Finite-Lived Intangible Assets, Gross								$ 15,100,000
Acquisition Costs Capitalized								40,000
InnoPran XL [Member]
INTANGIBLE ASSETS
Payments to Acquire Intangible Assets								$ 30,600,000
Finite-Lived Intangible Asset, Useful Life								10 years
Finite-Lived Intangible Assets, Gross								$ 19,000,000
Acquisition Costs Capitalized								$ 100,000
Teva Pharmaceuticals [Member]
INTANGIBLE ASSETS
Payments to Acquire Intangible Assets				$ 16,000,000
Cumulative Amortization Expense				$ 6,800,000
Acquired ANDA intangible assets [Member]
INTANGIBLE ASSETS
Finite-Lived Intangible Asset, Useful Life												10 years
Finite-Lived Intangible Assets, Gross										64,704,000		$ 64,704,000	46,194,000
Acquired ANDA intangible assets [Member] | IDT Australia Limited [Member]
INTANGIBLE ASSETS
Payments to Acquire Intangible Assets						$ 2,700,000
Finite-Lived Intangible Asset, Useful Life						10 years
Finite-Lived Intangible Assets, Gross						$ 2,500,000
Acquisition Costs Capitalized						$ 18,000
Acquired ANDA intangible assets [Member] | Teva Pharmaceuticals [Member]
INTANGIBLE ASSETS
Finite-Lived Intangible Asset, Useful Life			10 years
Finite-Lived Intangible Assets, Gross			$ 2,500,000
Acquisition Costs Capitalized			$ 10,000
Marketing and distribution rights
INTANGIBLE ASSETS
Finite-Lived Intangible Asset, Useful Life												4 years 8 months 12 days
Finite-Lived Intangible Assets, Gross										10,923,000		$ 10,923,000	10,423,000
Marketing and distribution rights | Pharmaceutics International, Inc and BAS ANDA LLC [Member]
INTANGIBLE ASSETS
Payments to Acquire Intangible Assets										500,000
Finite-Lived Intangible Asset, Useful Life												10 years
Marketing and distribution rights | Appco Pharma, LLC [Member]
INTANGIBLE ASSETS
Payments to Acquire Intangible Assets		80,000
Finite-Lived Intangible Assets, Gross		$ 80,000
Impairment of Intangible Assets, Finite-lived										75,000
New Drug Applications [Member] | Drug Applications and Marketing and Distribution Rights [Member]
INTANGIBLE ASSETS
Maximum Royalties Potentially Payable									$ 5,000,000
Royalty Rate									5.00%
Finite-Lived Intangible Assets, Gross										$ 10,900,000		$ 10,900,000
Impairment of Intangible Assets, Finite-lived												$ 75,000	$ 0	900,000	$ 6,700,000
Assets Held-for-sale, Not Part of Disposal Group, Current															$ 900,000
Abbreviated New Drug Applications [Member] | Impax Laboratories, Inc. [Member]
INTANGIBLE ASSETS
Payments to Acquire Intangible Assets					$ 2,300,000
Finite-Lived Intangible Asset, Useful Life					10 years
Finite-Lived Intangible Assets, Gross					$ 1,000,000
Acquisition Costs Capitalized					$ 100,000
New Drug Applications [Member] | Cranford Pharmaceuticals [Member]
INTANGIBLE ASSETS
Payments to Acquire Intangible Assets	$ 60,000,000
AstraZeneca AB and AstraZeneca UK Limited [Member] | New Drug Applications [Member]
INTANGIBLE ASSETS
Payments to Acquire Intangible Assets							$ 46,500,000
Finite-Lived Intangible Asset, Useful Life							10 years
Finite-Lived Intangible Assets, Gross							$ 46,700,000							$ 46,700,000
Acquisition Costs Capitalized							$ 200,000