REVENUE RECOGNITION AND RELATED ALLOWANCES - Accruals and Allowances (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	$ 59,946
Ending balance	104,771
Chargebacks
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	49,882	$ 39,007
Accruals/Adjustments	95,393	55,831
Credits Taken Against Reserve	(51,575)	(54,614)
Ending balance	93,700	40,224
Government Rebates
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	8,901	8,974
Accruals/Adjustments	3,567	2,381
Credits Taken Against Reserve	(4,438)	(2,803)
Ending balance	8,030	8,552
Returns
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	16,595	12,552
Accruals/Adjustments	5,937	3,620
Credits Taken Against Reserve	(4,918)	(2,613)
Ending balance	17,614	13,559
Administrative Fees and Other Rebates
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	8,281	7,353
Accruals/Adjustments	8,922	8,207
Credits Taken Against Reserve	(8,817)	(8,272)
Ending balance	8,386	7,288
Prompt Payment Discounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	2,549	2,009
Accruals/Adjustments	3,361	2,433
Credits Taken Against Reserve	(2,219)	(2,333)
Ending balance	$ 3,691	$ 2,109