REVENUES - Summary of Disaggregation of Revenues (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Disaggregation of Revenue [Line Items]
Total revenues	$ 6,352	$ 6,590
U.S.
Disaggregation of Revenue [Line Items]
Total revenues	4,452	4,355
Europe
Disaggregation of Revenue [Line Items]
Total revenues	1,079	1,202
Other International
Disaggregation of Revenue [Line Items]
Total revenues	821	1,033
Total product sales
Disaggregation of Revenue [Line Items]
Total revenues	6,306	6,534
Total product sales | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	4,434	4,329
Total product sales | Europe
Disaggregation of Revenue [Line Items]
Total revenues	1,053	1,174
Total product sales | Other International
Disaggregation of Revenue [Line Items]
Total revenues	819	1,031
Total HIV
Disaggregation of Revenue [Line Items]
Total revenues	4,190	3,707
Total HIV | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	3,364	2,862
Total HIV | Europe
Disaggregation of Revenue [Line Items]
Total revenues	528	550
Total HIV | Other International
Disaggregation of Revenue [Line Items]
Total revenues	298	295
Biktarvy
Disaggregation of Revenue [Line Items]
Total revenues	2,677	2,151
Biktarvy | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	2,161	1,706
Biktarvy | Europe
Disaggregation of Revenue [Line Items]
Total revenues	304	261
Biktarvy | Other International
Disaggregation of Revenue [Line Items]
Total revenues	212	184
Complera/Eviplera
Disaggregation of Revenue [Line Items]
Total revenues	39	44
Complera/Eviplera | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	14	17
Complera/Eviplera | Europe
Disaggregation of Revenue [Line Items]
Total revenues	22	24
Complera/Eviplera | Other International
Disaggregation of Revenue [Line Items]
Total revenues	3	4
Descovy
Disaggregation of Revenue [Line Items]
Total revenues	449	374
Descovy | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	395	311
Descovy | Europe
Disaggregation of Revenue [Line Items]
Total revenues	25	32
Descovy | Other International
Disaggregation of Revenue [Line Items]
Total revenues	29	31
Genvoya
Disaggregation of Revenue [Line Items]
Total revenues	501	582
Genvoya | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	417	457
Genvoya | Europe
Disaggregation of Revenue [Line Items]
Total revenues	55	77
Genvoya | Other International
Disaggregation of Revenue [Line Items]
Total revenues	29	48
Odefsey
Disaggregation of Revenue [Line Items]
Total revenues	317	339
Odefsey | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	230	232
Odefsey | Europe
Disaggregation of Revenue [Line Items]
Total revenues	76	96
Odefsey | Other International
Disaggregation of Revenue [Line Items]
Total revenues	11	11
Stribild
Disaggregation of Revenue [Line Items]
Total revenues	28	32
Stribild | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	20	22
Stribild | Europe
Disaggregation of Revenue [Line Items]
Total revenues	6	8
Stribild | Other International
Disaggregation of Revenue [Line Items]
Total revenues	2	3
Truvada
Disaggregation of Revenue [Line Items]
Total revenues	32	38
Truvada | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	23	28
Truvada | Europe
Disaggregation of Revenue [Line Items]
Total revenues	3	4
Truvada | Other International
Disaggregation of Revenue [Line Items]
Total revenues	5	6
Revenue share - Symtuza
Disaggregation of Revenue [Line Items]
Total revenues	138	132
Revenue share - Symtuza | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	98	86
Revenue share - Symtuza | Europe
Disaggregation of Revenue [Line Items]
Total revenues	36	44
Revenue share - Symtuza | Other International
Disaggregation of Revenue [Line Items]
Total revenues	4	3
Other HIV
Disaggregation of Revenue [Line Items]
Total revenues	9	14
Other HIV | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	4	5
Other HIV | Europe
Disaggregation of Revenue [Line Items]
Total revenues	1	4
Other HIV | Other International
Disaggregation of Revenue [Line Items]
Total revenues	3	5
Total Oncology
Disaggregation of Revenue [Line Items]
Total revenues	670	420
Total Oncology | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	431	292
Total Oncology | Europe
Disaggregation of Revenue [Line Items]
Total revenues	202	117
Total Oncology | Other International
Disaggregation of Revenue [Line Items]
Total revenues	37	11
Total Cell Therapy
Disaggregation of Revenue [Line Items]
Total revenues	448	274
Total Cell Therapy | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	269	172
Total Cell Therapy | Europe
Disaggregation of Revenue [Line Items]
Total revenues	148	92
Total Cell Therapy | Other International
Disaggregation of Revenue [Line Items]
Total revenues	31	10
Tecartus
Disaggregation of Revenue [Line Items]
Total revenues	89	63
Tecartus | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	59	47
Tecartus | Europe
Disaggregation of Revenue [Line Items]
Total revenues	27	15
Tecartus | Other International
Disaggregation of Revenue [Line Items]
Total revenues	3	1
Yescarta
Disaggregation of Revenue [Line Items]
Total revenues	359	211
Yescarta | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	210	125
Yescarta | Europe
Disaggregation of Revenue [Line Items]
Total revenues	121	77
Yescarta | Other International
Disaggregation of Revenue [Line Items]
Total revenues	28	9
Trodelvy
Disaggregation of Revenue [Line Items]
Total revenues	222	146
Trodelvy | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	162	119
Trodelvy | Europe
Disaggregation of Revenue [Line Items]
Total revenues	54	25
Trodelvy | Other International
Disaggregation of Revenue [Line Items]
Total revenues	6	2
Total Liver Disease
Disaggregation of Revenue [Line Items]
Total revenues	675	635
Total Liver Disease | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	318	279
Total Liver Disease | Europe
Disaggregation of Revenue [Line Items]
Total revenues	140	123
Total Liver Disease | Other International
Disaggregation of Revenue [Line Items]
Total revenues	217	233
Total HCV
Disaggregation of Revenue [Line Items]
Total revenues	445	399
Total HCV | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	232	199
Total HCV | Europe
Disaggregation of Revenue [Line Items]
Total revenues	114	95
Total HCV | Other International
Disaggregation of Revenue [Line Items]
Total revenues	99	105
Ledipasvir/Sofosbuvir
Disaggregation of Revenue [Line Items]
Total revenues	15	35
Ledipasvir/Sofosbuvir | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	3	13
Ledipasvir/Sofosbuvir | Europe
Disaggregation of Revenue [Line Items]
Total revenues	7	4
Ledipasvir/Sofosbuvir | Other International
Disaggregation of Revenue [Line Items]
Total revenues	5	18
Sofosbuvir/Velpatasvir
Disaggregation of Revenue [Line Items]
Total revenues	385	330
Sofosbuvir/Velpatasvir | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	204	162
Sofosbuvir/Velpatasvir | Europe
Disaggregation of Revenue [Line Items]
Total revenues	90	83
Sofosbuvir/Velpatasvir | Other International
Disaggregation of Revenue [Line Items]
Total revenues	90	85
Other HCV
Disaggregation of Revenue [Line Items]
Total revenues	45	34
Other HCV | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	24	24
Other HCV | Europe
Disaggregation of Revenue [Line Items]
Total revenues	18	8
Other HCV | Other International
Disaggregation of Revenue [Line Items]
Total revenues	4	2
Total HBV/HDV
Disaggregation of Revenue [Line Items]
Total revenues	230	235
Total HBV/HDV | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	86	80
Total HBV/HDV | Europe
Disaggregation of Revenue [Line Items]
Total revenues	26	28
Total HBV/HDV | Other International
Disaggregation of Revenue [Line Items]
Total revenues	117	128
Vemlidy
Disaggregation of Revenue [Line Items]
Total revenues	199	200
Vemlidy | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	87	80
Vemlidy | Europe
Disaggregation of Revenue [Line Items]
Total revenues	9	9
Vemlidy | Other International
Disaggregation of Revenue [Line Items]
Total revenues	103	111
Viread
Disaggregation of Revenue [Line Items]
Total revenues	19	23
Viread | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	(1)	0
Viread | Europe
Disaggregation of Revenue [Line Items]
Total revenues	6	6
Viread | Other International
Disaggregation of Revenue [Line Items]
Total revenues	14	17
Other HBV/HBD
Disaggregation of Revenue [Line Items]
Total revenues	11	13
Other HBV/HBD | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Other HBV/HBD | Europe
Disaggregation of Revenue [Line Items]
Total revenues	11	13
Other HBV/HBD | Other International
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Veklury
Disaggregation of Revenue [Line Items]
Total revenues	573	1,535
Veklury | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	252	801
Veklury | Europe
Disaggregation of Revenue [Line Items]
Total revenues	111	304
Veklury | Other International
Disaggregation of Revenue [Line Items]
Total revenues	209	430
Total Other
Disaggregation of Revenue [Line Items]
Total revenues	199	236
Total Other | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	69	94
Total Other | Europe
Disaggregation of Revenue [Line Items]
Total revenues	72	81
Total Other | Other International
Disaggregation of Revenue [Line Items]
Total revenues	58	62
AmBisome
Disaggregation of Revenue [Line Items]
Total revenues	116	144
AmBisome | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	6	25
AmBisome | Europe
Disaggregation of Revenue [Line Items]
Total revenues	60	66
AmBisome | Other International
Disaggregation of Revenue [Line Items]
Total revenues	49	53
Letairis
Disaggregation of Revenue [Line Items]
Total revenues	32	43
Letairis | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	32	43
Letairis | Europe
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Letairis | Other International
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Other
Disaggregation of Revenue [Line Items]
Total revenues	51	50
Other | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	30	26
Other | Europe
Disaggregation of Revenue [Line Items]
Total revenues	12	15
Other | Other International
Disaggregation of Revenue [Line Items]
Total revenues	9	9
Royalty, contract and other revenues
Disaggregation of Revenue [Line Items]
Total revenues	46	56
Royalty, contract and other revenues | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	18	27
Royalty, contract and other revenues | Europe
Disaggregation of Revenue [Line Items]
Total revenues	26	27
Royalty, contract and other revenues | Other International
Disaggregation of Revenue [Line Items]
Total revenues	$ 2	$ 3