CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net (Loss)/Earnings	$ (8,995)	$ 3,460	$ 4,947
Other Comprehensive Income (Loss), net of taxes and reclassifications to earnings [Abstract]
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax	(256)	(32)	70
Pension and postretirement benefits	(75)	1,203	53
Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, after Tax	5	36	(25)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	7	35	(254)
Other Comprehensive Income (Loss), Net of Tax	(319)	1,242	(156)
Comprehensive (Loss)/Income	(9,314)	4,702	4,791
Comprehensive (Loss)/Income Attributable to BMS	(9,334)	4,681	4,764
Noncontrolling Interest	$ 20	$ 21	$ 27