EQUITY (Changes in Equity) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2019	Jan. 01, 2018
Equity [Line Items]
Common Stock, Dividends, Per Share, Declared	$ 0.49	$ 0.45	$ 0.45	$ 0.45	$ 0.45	$ 0.41	$ 0.41	$ 0.41	$ 1.84	$ 1.68	$ 1.61
Common Stock, Value, Issued, Balance at January 1,				$ 292					$ 292
Common Stock, Value, Issued, Balance at December 31,	$ 292				$ 292				292	$ 292
Capital in Excess of Par Value of Stock, Balance at January 1,				43,709					43,709
Capital in Excess of Par Value of Stock, Balance at December 31,	44,325				43,709				44,325	43,709
Accumulated Other Comprehensive Loss, Balance at January 1				(1,520)					(1,520)
Other Comprehensive Income (Loss), Net of Tax									(319)	1,242	$ (156)
Accumulated Other Comprehensive Loss, Balance at December 31	(1,839)				(1,520)				(1,839)	(1,520)
Retained Earnings, Balance at January 1,				34,474					34,474
Net (Loss)/Earnings Attributable to BMS	(10,027)	$ 1,872	$ (85)	$ (775)	(1,056)	$ 1,353	$ 1,432	$ 1,710	(9,015)	3,439	4,920
Retained Earnings, Balance at December 31,	$ 21,281				$ 34,474				$ 21,281	$ 34,474
Treasury Stock, Shares, Balance at January 1,				672					672
Treasury Stock, Shares, Balance at December 31,	679				672				679	672
Cost of Treasury Stock, Balance at January 1,				$ (25,357)					$ (25,357)
Cost of Treasury Stock, Balance at December 31,	$ (26,237)				$ (25,357)				(26,237)	$ (25,357)
Noncontrolling interest, Balance at January 1,				100					100
Noncontrolling Interest	0	$ 6	$ 5	$ 9	(4)	$ 13	$ 7	$ 5	20	21	$ 27
Noncontrolling interest, Balance at December 31,	$ 60				$ 100				$ 60	$ 100
Accumulated Other Comprehensive Loss Cumulative Adjustments												$ 0	$ (34)
Common Stock [Member]
Equity [Line Items]
Common Stock, Shares Issued, Balance at January 1,				2,923				2,208	2,923	2,208	2,208
Common Stock, Shares Issued, Balance at December 31,	2,923				2,923				2,923	2,923	2,208
Common Stock, Value, Issued, Balance at January 1,				$ 292				$ 221	$ 292	$ 221	$ 221
Common Stock, Value, Issued, Balance at December 31,	$ 292				$ 292				292	$ 292	221
Stock Issued During Period, Shares, New Issues										715
Stock Issued During Period, Value, New Issues										$ 71
Capital in Excess of Par Value of Stock [Member]
Equity [Line Items]
Capital in Excess of Par Value of Stock, Balance at January 1,				43,709				2,081	43,709	2,081	1,898
Capital in Excess of Par Value of Stock, Balance at December 31,	44,325				43,709				44,325	43,709	2,081
Stock compensation									(784)	307	183
Stock Issued During Period, Value, New Issues										42,721
Stock repurchase program, Cost of Treasury Stock									(1,400)
Accumulated Other Comprehensive Loss [Member]
Equity [Line Items]
Accumulated Other Comprehensive Loss, Balance at January 1				(1,520)				(2,762)	(1,520)	(2,762)	(2,289)
Other Comprehensive Income (Loss), Net of Tax									(319)	1,242	(156)
Accumulated Other Comprehensive Loss, Balance at December 31	(1,839)				(1,520)				(1,839)	(1,520)	(2,762)
New Accounting Pronoucement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets											(283)
Accumulated Other ComprehensiveIncome Loss Net Of Tax, Adjusted Balance												(2,762)	(2,323)
Retained Earnings [Member]
Equity [Line Items]
Retained Earnings, Balance at January 1,				$ 34,474				$ 34,065	34,474	34,065	31,160
Net (Loss)/Earnings Attributable to BMS									(9,015)	3,439	4,920
Cash dividends declared									(4,178)	(3,035)	(2,630)
Retained Earnings, Balance at December 31,	$ 21,281				$ 34,474				$ 21,281	$ 34,474	34,065
New Accounting Pronoucement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets											$ 283
RetainedEarningsCumulativeAdjustments												5	332
Retained Earnings Accumulated Deficit, Adjusted Balance												$ 34,070	$ 31,492
Treasury Stock [Member]
Equity [Line Items]
Treasury Stock, Shares, Balance at January 1,				672				576	672	576	575
Stock repurchase program, Treasury Stock									43	105	5
Employee stock compensation plans, Shares									(36)	(9)	(4)
Treasury Stock, Shares, Balance at December 31,	679				672				679	672	576
Cost of Treasury Stock, Balance at January 1,				$ (25,357)				$ (19,574)	$ (25,357)	$ (19,574)	$ (19,249)
Stock repurchase program, Cost of Treasury Stock									(2,993)	(5,900)	(313)
Employee stock compensation plans, Cost									2,113	117	(12)
Cost of Treasury Stock, Balance at December 31,	$ (26,237)				$ (25,357)				(26,237)	(25,357)	(19,574)
Noncontrolling Interest [Member]
Equity [Line Items]
Noncontrolling interest, Balance at January 1,				$ 100				$ 96	100	96	106
Noncontrolling Interest									(20)	(21)	(27)
Distributions									(60)	(17)	(37)
Noncontrolling interest, Balance at December 31,	$ 60				$ 100				$ 60	$ 100	$ 96