PENSION AND POSTRETIREMENT BENEFIT PLANS (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Payment for Pension Benefits		$ 1,300
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement		(1,500)
Net periodic benefit cost/(credit)		1,537	$ (10)	$ 1,607	$ (40)
Non-current pension liabilities		426		426		$ 427
Defined contribution plan expense		50	50	140	130
Pension Benefits [Member]
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Service cost - benefits earned during the period		6	6	18	20
Interest cost on projected benefit obligation		20	50	101	146
Expected return on plan assets		(39)	(97)	(173)	(315)
Amortization of prior service credits		(1)	(1)	(3)	(3)
Amortization of net actuarial (gain)/loss		14	17	49	57
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment		1,550	26	1,643	95
Net periodic benefit cost/(credit)		1,550	$ 1	1,635	$ 0
Bristol-Myers Squibb Retirement Income Plan [Member]
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Defined Benefit Plan, Benefit Obligation		$ 2,400		$ 2,400
Forecast [Member]
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Payment for Pension Benefits	$ 200