PENSION AND POSTRETIREMENT BENEFIT PLANS (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Defined Benefit Plan Principal Pension Plan Assets Percentage		67.00%		67.00%
Defined Benefit Plan Principal Pension Plan Obligations Percentage		61.00%		61.00%
Net periodic benefit cost/(credit)		$ 26	$ (19)	$ 70	$ (30)
Non-current pension liabilities		423		423		$ 427
Defined contribution plan expense			50		90
Pension Benefits [Member]
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Service cost - benefits earned during the period		5	7	12	14
Interest cost on projected benefit obligation		37	50	81	96
Expected return on plan assets		(70)	(109)	(134)	(218)
Amortization of prior service credits		(1)	(1)	(2)	(2)
Amortization of net actuarial (gain)/loss		17	19	35	40
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment		44	38	93	69
Net periodic benefit cost/(credit)		$ 32	$ 4	$ 85	$ (1)
Bristol-Myers Squibb Retirement Income Plan [Member]
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Defined Benefit Plan, Benefit Obligation						$ 3,800
Scenario, Forecast [Member]
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	$ 1,500