REVENUES - Summary of Disaggregation of Revenues (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue [Line Items]
Total revenues	$ 6,686	$ 6,352
U.S.
Disaggregation of Revenue [Line Items]
Total revenues	4,633	4,452
Europe
Disaggregation of Revenue [Line Items]
Total revenues	1,159	1,079
Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	894	821
Total product sales
Disaggregation of Revenue [Line Items]
Total revenues	6,647	6,306
Total product sales | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	4,609	4,434
Total product sales | Europe
Disaggregation of Revenue [Line Items]
Total revenues	1,144	1,053
Total product sales | Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	894	819
Total HIV
Disaggregation of Revenue [Line Items]
Total revenues	4,342	4,190
Total HIV | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	3,405	3,364
Total HIV | Europe
Disaggregation of Revenue [Line Items]
Total revenues	596	528
Total HIV | Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	342	298
Biktarvy
Disaggregation of Revenue [Line Items]
Total revenues	2,946	2,677
Biktarvy | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	2,315	2,161
Biktarvy | Europe
Disaggregation of Revenue [Line Items]
Total revenues	365	304
Biktarvy | Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	265	212
Descovy
Disaggregation of Revenue [Line Items]
Total revenues	426	449
Descovy | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	371	395
Descovy | Europe
Disaggregation of Revenue [Line Items]
Total revenues	26	25
Descovy | Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	29	29
Genvoya
Disaggregation of Revenue [Line Items]
Total revenues	403	501
Genvoya | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	332	417
Genvoya | Europe
Disaggregation of Revenue [Line Items]
Total revenues	49	55
Genvoya | Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	21	29
Odefsey
Disaggregation of Revenue [Line Items]
Total revenues	310	317
Odefsey | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	223	230
Odefsey | Europe
Disaggregation of Revenue [Line Items]
Total revenues	76	76
Odefsey | Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	11	11
Revenue share - Symtuza
Disaggregation of Revenue [Line Items]
Total revenues	141	138
Revenue share - Symtuza | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	104	98
Revenue share - Symtuza | Europe
Disaggregation of Revenue [Line Items]
Total revenues	33	36
Revenue share - Symtuza | Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	3	4
Other HIV
Disaggregation of Revenue [Line Items]
Total revenues	117	108
Other HIV | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	60	62
Other HIV | Europe
Disaggregation of Revenue [Line Items]
Total revenues	45	32
Other HIV | Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	12	13
Total Liver Disease
Disaggregation of Revenue [Line Items]
Total revenues	737	675
Total Liver Disease | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	385	318
Total Liver Disease | Europe
Disaggregation of Revenue [Line Items]
Total revenues	137	140
Total Liver Disease | Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	215	217
Sofosbuvir/Velpatasvir
Disaggregation of Revenue [Line Items]
Total revenues	405	385
Sofosbuvir/Velpatasvir | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	248	204
Sofosbuvir/Velpatasvir | Europe
Disaggregation of Revenue [Line Items]
Total revenues	79	90
Sofosbuvir/Velpatasvir | Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	78	90
Vemlidy
Disaggregation of Revenue [Line Items]
Total revenues	225	199
Vemlidy | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	95	87
Vemlidy | Europe
Disaggregation of Revenue [Line Items]
Total revenues	11	9
Vemlidy | Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	119	103
Other Liver Disease
Disaggregation of Revenue [Line Items]
Total revenues	107	91
Other Liver Disease | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	42	27
Other Liver Disease | Europe
Disaggregation of Revenue [Line Items]
Total revenues	47	41
Other Liver Disease | Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	19	23
Veklury
Disaggregation of Revenue [Line Items]
Total revenues	555	573
Veklury | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	315	252
Veklury | Europe
Disaggregation of Revenue [Line Items]
Total revenues	70	111
Veklury | Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	169	209
Total Oncology
Disaggregation of Revenue [Line Items]
Total revenues	789	670
Total Oncology | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	431	431
Total Oncology | Europe
Disaggregation of Revenue [Line Items]
Total revenues	262	202
Total Oncology | Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	96	37
Total Cell Therapy
Disaggregation of Revenue [Line Items]
Total revenues	480	448
Total Cell Therapy | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	225	269
Total Cell Therapy | Europe
Disaggregation of Revenue [Line Items]
Total revenues	195	148
Total Cell Therapy | Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	60	31
Tecartus
Disaggregation of Revenue [Line Items]
Total revenues	100	89
Tecartus | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	55	59
Tecartus | Europe
Disaggregation of Revenue [Line Items]
Total revenues	36	27
Tecartus | Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	8	3
Yescarta
Disaggregation of Revenue [Line Items]
Total revenues	380	359
Yescarta | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	170	210
Yescarta | Europe
Disaggregation of Revenue [Line Items]
Total revenues	158	121
Yescarta | Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	52	28
Trodelvy
Disaggregation of Revenue [Line Items]
Total revenues	309	222
Trodelvy | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	206	162
Trodelvy | Europe
Disaggregation of Revenue [Line Items]
Total revenues	68	54
Trodelvy | Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	36	6
Total Other
Disaggregation of Revenue [Line Items]
Total revenues	224	199
Total Other | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	73	69
Total Other | Europe
Disaggregation of Revenue [Line Items]
Total revenues	79	72
Total Other | Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	71	58
AmBisome
Disaggregation of Revenue [Line Items]
Total revenues	144	116
AmBisome | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	14	6
AmBisome | Europe
Disaggregation of Revenue [Line Items]
Total revenues	70	60
AmBisome | Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	60	49
Other
Disaggregation of Revenue [Line Items]
Total revenues	80	83
Other | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	59	62
Other | Europe
Disaggregation of Revenue [Line Items]
Total revenues	9	12
Other | Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	12	9
Royalty, contract and other revenues
Disaggregation of Revenue [Line Items]
Total revenues	39	46
Royalty, contract and other revenues | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	23	18
Royalty, contract and other revenues | Europe
Disaggregation of Revenue [Line Items]
Total revenues	15	26
Royalty, contract and other revenues | Rest of World
Disaggregation of Revenue [Line Items]
Total revenues	$ 1	$ 2