DIVESTITURES (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Divestiture of Businesses, Net of Cash Divested	$ 171	$ 375
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal	0	(45)
Business Sale Royalty Income	(166)	(210)
Diabetes business [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Divestiture of Businesses, Net of Cash Divested	164	88
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal	0	0
Business Sale Royalty Income	(165)	(162)
Erbitux [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Divestiture of Businesses, Net of Cash Divested	5	59
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal	0	0
Business Sale Royalty Income	0	(47)
Manufacturing Facility in Swords, Ireland [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Divestiture of Businesses, Net of Cash Divested	2	158
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal	0	0
Business Sale Royalty Income	0	0
Initial divestiture proceeds received in Q1 2018		158
Other divestitures [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Divestiture of Businesses, Net of Cash Divested	0	70
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal	0	(45)
Business Sale Royalty Income	$ (1)	$ (1)
Scenario, Plan [Member] | Manufacturing Facility in Swords, Ireland [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Divestiture of Businesses, Net of Cash Divested			$ 165