GOODWILL AND INTANGIBLE ASSETS - Components (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
INTANGIBLE ASSETS
Gross Carrying Amount	$ 355,170		$ 355,170
Accumulated Amortization	(176,311)		$ (166,659)
Weighted Average Amortization Period			9 years 4 months 24 days
Amortization of intangible assets	9,700	$ 10,000
Intangible asset impairment charge	0	$ 0
Acquired ANDA intangible assets
INTANGIBLE ASSETS
Gross Carrying Amount	106,415		$ 106,415
Accumulated Amortization	$ (45,473)		(42,367)
Weighted Average Amortization Period	8 years 9 months 18 days
NDAs and product rights
INTANGIBLE ASSETS
Gross Carrying Amount	$ 230,974		230,974
Accumulated Amortization	$ (118,766)		(112,483)
Weighted Average Amortization Period	10 years
Marketing and distribution rights
INTANGIBLE ASSETS
Gross Carrying Amount	$ 17,157		17,157
Accumulated Amortization	$ (11,626)		(11,386)
Weighted Average Amortization Period	5 years 8 months 12 days
Non-compete agreement
INTANGIBLE ASSETS
Gross Carrying Amount	$ 624		624
Accumulated Amortization	$ (446)		$ (423)
Weighted Average Amortization Period	7 years

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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