ACQUISITION, LICENSING AGREEMENTS AND ASSETS HELD FOR SALE - Narrative (Details)			3 Months Ended		9 Months Ended		10 Months Ended	12 Months Ended
	Sep. 21, 2020 USD ($)	Mar. 06, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) product	Dec. 31, 2019 USD ($) product	Dec. 31, 2018 USD ($)	Mar. 31, 2020 USD ($)
Business Acquisition [Line Items]
Other expense, net			$ 16,000,000	$ 10,000,000	$ 146,000,000	$ 15,000,000
Assets reclassified, held and used			31,562,000,000		$ 31,562,000,000		$ 33,863,000,000	$ 33,863,000,000
Disposal Group, Held-for-sale, Not Discontinued Operations | Certain Products For Disposal, September 2019
Business Acquisition [Line Items]
Revenue associated with products for disposal								$ 14,000,000	$ 19,000,000
Impairment of long-lived assets classified as held for sale				$ 8,000,000		8,000,000
Disposal Group, Held-for-sale, Not Discontinued Operations | Certain Products For Disposal, September 2019 | Restatement Adjustment
Business Acquisition [Line Items]
Assets reclassified, held for sale										$ 39,000,000
Assets reclassified, held and used										$ 39,000,000
Disposal Group, Held-for-sale, Not Discontinued Operations | Certain Products For Disposal, September 2019 | Diversified Products
Business Acquisition [Line Items]
Number of products for disposal | product							1	1
Allegro
Business Acquisition [Line Items]
Other expense, net			$ 10,000,000
Potential asset acquisition, aggregate purchase price	$ 50,000,000
Potential asset acquisition, upfront payment included in aggregate purchase price	10,000,000
Potential asset acquisition, additional funding payment included in aggregate purchase price	$ 40,000,000
Synergy Pharmaceuticals Inc.
Business Acquisition [Line Items]
Cash payments to acquire certain assets and assumed liabilities		$ 180,000,000
Revenue of acquiree							$ 55,000,000
Operating results of acquiree							$ 0
Pro forma revenue						0		$ 0
Pro forma operating results						0		$ 0
Other expense, net						$ 8,000,000