PENSION AND POSTRETIREMENT BENEFIT PLANS PENSION AND POSTRETIREMENT BENEFIT PLANS (Defined Benefit Pension Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Document Period End Date	Dec. 31, 2020
Pension Plans, Defined Benefit [Member]
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Defined Benefit Plan, Benefit Obligation	$ 3,242	$ 2,940	$ 5,966
Funded Status	(435)	$ (404)
Bristol-Myers Squibb Retirement Income Plan [Member]
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Payment for Pension Benefits	1,300
Defined Benefit Plan, Benefit Obligation	2,600
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	1,500
Bristol-Myers Squibb Retirement Income Plan [Member] | Pension Plans, Defined Benefit [Member]
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Funded Status	$ 424