REVENUE RECOGNITION - Variable Consideration Provisions (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Reserve beginning balance	$ 2,050	$ 2,384
Acquisition of Synergy		16
Current period provisions	2,377	2,612
Payments and credits	(2,586)	(2,751)
Reserve ending balance	1,841	2,261
Discounts and Allowances
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Reserve beginning balance	182	175
Acquisition of Synergy		0
Current period provisions	293	406
Payments and credits	(316)	(408)
Reserve ending balance	159	173
Returns
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Reserve beginning balance	691	813
Acquisition of Synergy		3
Current period provisions	54	78
Payments and credits	(124)	(120)
Reserve ending balance	621	774
Rebates
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Reserve beginning balance	927	1,024
Acquisition of Synergy		12
Current period provisions	1,018	1,100
Payments and credits	(1,096)	(1,125)
Reserve ending balance	849	1,011
Chargebacks
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Reserve beginning balance	168	209
Acquisition of Synergy		0
Current period provisions	917	930
Payments and credits	(939)	(979)
Reserve ending balance	146	160
Distribution Fees
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Reserve beginning balance	82	163
Acquisition of Synergy		1
Current period provisions	95	98
Payments and credits	(111)	(119)
Reserve ending balance	$ 66	$ 143