REVENUE RECOGNITION - Variable Consideration Provisions (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Reserve beginning balance	$ 2,384	$ 2,546
Acquisition of Synergy	16
Current period provisions	3,860	4,468
Payments and credits	(4,104)	(4,514)
Reserve ending balance	2,156	2,500
Discounts and Allowances
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Reserve beginning balance	175	167
Acquisition of Synergy	0
Current period provisions	585	643
Payments and credits	(583)	(632)
Reserve ending balance	177	178
Returns
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Reserve beginning balance	813	863
Acquisition of Synergy	3
Current period provisions	50	209
Payments and credits	(187)	(264)
Reserve ending balance	679	808
Rebates
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Reserve beginning balance	1,024	1,094
Acquisition of Synergy	12
Current period provisions	1,650	1,976
Payments and credits	(1,673)	(1,939)
Reserve ending balance	1,013	1,131
Chargebacks
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Reserve beginning balance	209	274
Acquisition of Synergy	0
Current period provisions	1,425	1,462
Payments and credits	(1,480)	(1,512)
Reserve ending balance	154	224
Distribution Fees
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Reserve beginning balance	163	148
Acquisition of Synergy	1
Current period provisions	150	178
Payments and credits	(181)	(167)
Reserve ending balance	$ 133	$ 159