SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) - USD ($) $ 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
Revenues	$ 11,068	$ 10,540	$ 10,129	$ 10,781	$ 7,945	$ 6,007	$ 6,273	$ 5,920	$ 42,518	$ 26,145
Gross Margin	8,158	8,038	7,430	7,119	5,453	4,217	4,301	4,096	30,745	18,067
Net (Loss)/Earnings	(10,027)	1,878	(80)	(766)	(1,060)	1,366	1,439	1,715	(8,995)	3,460
Noncontrolling Interest	0	6	5	9	(4)	13	7	5	20	21
Net (Loss)/Earnings Attributable to BMS	$ (10,027)	$ 1,872	$ (85)	$ (775)	$ (1,056)	$ 1,353	$ 1,432	$ 1,710	$ (9,015)	$ 3,439
Basic Earnings Per Common Share Attributable to BMS	$ (4.45)	$ 0.83	$ (0.04)	$ (0.34)	$ (0.55)	$ 0.83	$ 0.88	$ 1.05	$ (3.99)	$ 2.02
Diluted Earnings per Common Share Attributable to BMS	(4.45)	0.82	(0.04)	(0.34)	(0.55)	0.83	0.87	1.04	(3.99)	2.01
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
Cash and cash equivalents	$ 14,546	$ 19,435	$ 19,934	$ 15,817	$ 12,346	$ 30,489	$ 28,404	$ 7,335	$ 14,546	$ 12,346
Marketable Securities	1,718	2,215	2,247	3,156	3,814	2,978	1,947	2,662	1,718	3,814
Total Assets	118,481	125,536	128,076	129,285	129,944	57,433	55,163	34,834	118,481	129,944
Long-term Debt	50,336	44,614	46,106	46,105	46,150	24,390	24,433	5,635	50,336	46,150
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	37,882	50,230	49,160	49,977	51,698	17,754	16,151	15,317	37,882	51,698
Increase/(decrease) to pretax income	14,392	2,256	2,730	5,022	2,886	840	612	137	24,400	4,475
Cost of products sold	675	459	728	1,438	685	22	139	12	3,300	858
Marketing, selling and administrative	241	6	11	21	35	0	0	1	279	36
Research and development	1,213	223	354	116	142	20	44	51	1,906	257
IPRD charge - MyoKardia acquisition - Specified Items	11,438								11,438
Amortization of Acquired Intangible Assets - Specified Items	2,526	2,491	2,389	2,282	1,062				9,688	1,062
Other income (net)	(1,701)	(923)	(752)	1,165	962	798	429	73	(2,211)	2,262
Income Tax On Items Affecting Comparability	(1,034)	(405)	(3)	(291)	(264)	(275)	(105)	(43)	(1,733)	(687)
Otezla Divestiture Tax Impact - Specified		11	255						266
Income taxes attributed to internal transfer of intangible assets			853		808				853	808
Income Tax - Specified Items	(1,034)	(394)	1,105	(291)	544	(275)	(105)	(43)	(614)	121
Increase/(decrease) to Net Earnings	13,358	1,862	3,835	4,731	3,430	565	507	94	23,786	4,596
Inventory purchase price accounting adjustments | Cost of products sold [Member]
Increase/(decrease) to pretax income	98	456	714	1,420	660				2,688	660
Inventory purchase price accounting adjustments | Research and development [Member]
Increase/(decrease) to pretax income	11	8	0	17					36
Intangible asset impairment [Member] | Cost of products sold [Member]
Increase/(decrease) to pretax income	575								575
Employee compensation charges [Member] | Cost of products sold [Member]
Increase/(decrease) to pretax income	1		1	2	1				4	1
Employee compensation charges [Member] | Selling, General and Administrative Expenses [Member]
Increase/(decrease) to pretax income	241	7	12	15	27				275	27
Employee compensation charges [Member] | Research and development [Member]
Increase/(decrease) to pretax income	241	8	15	18	33				282	33
Accelerated Depreciation and Other Shutdown Costs [Member] | Cost of products sold [Member]
Increase/(decrease) to pretax income	1	3	13	16	24	22	139	12	33	197
Accelerated Depreciation and Other Shutdown Costs [Member] | Selling, General and Administrative Expenses [Member]
Increase/(decrease) to pretax income	0	(1)	(1)	6	8			1	4	9
Accelerated Depreciation and Other Shutdown Costs [Member] | Research and development [Member]
Increase/(decrease) to pretax income	16	4	39	56	109	20	19	19	115	167
Upfront, milestone and other licensing payments [Member]
Increase/(decrease) to pretax income					0	0	25	0		25
Upfront, milestone and other licensing payments [Member] | Research and development [Member]
Increase/(decrease) to pretax income	475	203	300	25					1,003
IPRD Impairments [Member] | Research and development [Member]
Increase/(decrease) to pretax income	470	0	0	0				32	470	32
Interest Expense [Member]
Increase/(decrease) to pretax income	(37)	(40)	(41)	(41)	73	166	83		(159)	322
Contingent Value Rights [Member]
Increase/(decrease) to pretax income	(1,160)	(988)	(165)	556	523				(1,757)	523
Royalties and licensing income [Member]
Increase/(decrease) to pretax income	(14)	(53)	(18)	(83)	(15)	(9)	0	0	(168)	(24)
Loss/(gain) on equity investments [Member]
Increase/(decrease) to pretax income	(463)	(214)	(818)	339	(294)	261	(71)	(175)	(1,156)	(279)
Integration expenses [Member]
Increase/(decrease) to pretax income	182	195	166	174	191	96	106	22	717	415
Provision For Restructuring [Member]
Increase/(decrease) to pretax income	79	176	115	160	269	10	10	12	530	301
Litigation Charges Recoveries [Member]
Increase/(decrease) to pretax income	(239)	0	0	0	75	0	0	0	(239)	75
Reversion excise tax
Increase/(decrease) to pretax income	0	0	0	76					76
Divestiture gains [Member]
Increase/(decrease) to pretax income	$ (49)	$ 1	$ 9	$ (16)	3	(1,179)	8	0	$ (55)	(1,168)
Investment Income [Member]
Increase/(decrease) to pretax income					(44)	(99)	(54)			(197)
Pension charges [Member]
Increase/(decrease) to pretax income					(3)	1,545	44	49		1,635
Acquisition expenses [Member]
Increase/(decrease) to pretax income					182	7	303	165		657
Other Expense [Member]
Increase/(decrease) to pretax income					$ 2	$ 0	$ 0	$ 0		$ 2