Revenues - Disaggregation of Revenues (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Total revenues	$ 27,305	$ 24,689	$ 22,449
U.S.
Disaggregation of Revenue [Line Items]
Total revenues	19,267	18,217	16,645
Europe
Disaggregation of Revenue [Line Items]
Total revenues	4,874	4,135	3,811
Other International
Disaggregation of Revenue [Line Items]
Total revenues	3,164	2,337	1,993
Product sales
Disaggregation of Revenue [Line Items]
Total revenues	27,008	24,355	22,119
Product sales \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	19,176	18,141	16,565
Product sales \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	4,678	3,894	3,567
Product sales \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	3,154	2,320	1,987
Total HIV
Disaggregation of Revenue [Line Items]
Total revenues	16,315	16,938	16,438
Total HIV \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	12,828	13,651	13,315
Total HIV \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	2,366	2,287	2,312
Total HIV \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	1,121	1,000	811
Atripla
Disaggregation of Revenue [Line Items]
Total revenues	145	349	600
Atripla \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	121	307	501
Atripla \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	12	21	60
Atripla \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	12	21	39
Biktarvy
Disaggregation of Revenue [Line Items]
Total revenues	8,624	7,259	4,738
Biktarvy \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	7,049	6,095	4,225
Biktarvy \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	969	735	370
Biktarvy \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	606	429	143
Complera/Eviplera
Disaggregation of Revenue [Line Items]
Total revenues	258	269	406
Complera/Eviplera \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	102	89	160
Complera/Eviplera \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	142	159	214
Complera/Eviplera \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	14	21	32
Descovy
Disaggregation of Revenue [Line Items]
Total revenues	1,700	1,861	1,500
Descovy \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	1,397	1,526	1,078
Descovy \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	164	197	255
Descovy \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	139	138	167
Genvoya
Disaggregation of Revenue [Line Items]
Total revenues	2,879	3,338	3,931
Genvoya \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	2,267	2,605	2,984
Genvoya \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	391	490	664
Genvoya \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	221	243	283
Odefsey
Disaggregation of Revenue [Line Items]
Total revenues	1,568	1,672	1,655
Odefsey \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	1,076	1,172	1,180
Odefsey \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	440	450	438
Odefsey \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	52	50	37
Stribild
Disaggregation of Revenue [Line Items]
Total revenues	189	196	369
Stribild \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	132	125	268
Stribild \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	43	54	75
Stribild \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	14	17	26
Truvada
Disaggregation of Revenue [Line Items]
Total revenues	371	1,448	2,813
Truvada \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	314	1,376	2,640
Truvada \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	22	27	101
Truvada \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	35	45	72
Revenue share - Symtuza
Disaggregation of Revenue [Line Items]
Total revenues	531	488	379
Revenue share - Symtuza \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	355	331	249
Revenue share - Symtuza \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	165	149	130
Revenue share - Symtuza \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	11	8	0
Other HIV
Disaggregation of Revenue [Line Items]
Total revenues	50	58	47
Other HIV \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	15	25	30
Other HIV \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	18	5	5
Other HIV \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	17	28	12
Veklury
Disaggregation of Revenue [Line Items]
Total revenues	5,565	2,811	0
Veklury \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	3,640	2,026	0
Veklury \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	1,095	607	0
Veklury \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	830	178	0
Total HCV
Disaggregation of Revenue [Line Items]
Total revenues	1,881	2,064	2,936
Total HCV \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	1,018	1,088	1,465
Total HCV \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	421	414	742
Total HCV \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	442	562	729
Ledipasvir/Sofosbuvir
Disaggregation of Revenue [Line Items]
Total revenues	212	272	643
Ledipasvir/Sofosbuvir \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	84	92	312
Ledipasvir/Sofosbuvir \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	31	29	71
Ledipasvir/Sofosbuvir \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	97	151	260
Sofosbuvir/Velpatasvir
Disaggregation of Revenue [Line Items]
Total revenues	1,462	1,599	1,965
Sofosbuvir/Velpatasvir \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	815	864	971
Sofosbuvir/Velpatasvir \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	316	337	553
Sofosbuvir/Velpatasvir \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	331	398	441
Other HCV
Disaggregation of Revenue [Line Items]
Total revenues	207	193	328
Other HCV \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	119	132	182
Other HCV \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	74	48	118
Other HCV \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	14	13	28
Total HBV/HDV
Disaggregation of Revenue [Line Items]
Total revenues	969	860	742
Total HBV/HDV \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	397	380	343
Total HBV/HDV \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	104	71	99
Total HBV/HDV \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	468	409	300
Vemlidy
Disaggregation of Revenue [Line Items]
Total revenues	814	657	488
Vemlidy \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	384	356	309
Vemlidy \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	34	29	21
Vemlidy \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	396	272	158
Viread
Disaggregation of Revenue [Line Items]
Total revenues	111	185	243
Viread \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	11	14	32
Viread \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	28	34	69
Viread \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	72	137	142
Other HB/HDV
Disaggregation of Revenue [Line Items]
Total revenues	44	18	11
Other HB/HDV \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	2	10	2
Other HB/HDV \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	42	8	9
Other HB/HDV \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Total Cell Therapy
Disaggregation of Revenue [Line Items]
Total revenues	871	607	456
Total Cell Therapy \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	542	396	373
Total Cell Therapy \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	293	201	83
Total Cell Therapy \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	36	10	0
Tecartus
Disaggregation of Revenue [Line Items]
Total revenues	176	44	0
Tecartus \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	136	34	0
Tecartus \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	40	10	0
Tecartus \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Yescarta
Disaggregation of Revenue [Line Items]
Total revenues	695	563	456
Yescarta \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	406	362	373
Yescarta \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	253	191	83
Yescarta \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	36	10	0
Trodelvy
Disaggregation of Revenue [Line Items]
Total revenues	380	49	0
Trodelvy \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	370	49	0
Trodelvy \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	10	0	0
Trodelvy \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Total Other
Disaggregation of Revenue [Line Items]
Total revenues	1,027	1,026	1,547
Total Other \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	381	551	1,069
Total Other \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	389	314	331
Total Other \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	257	161	147
AmBisome
Disaggregation of Revenue [Line Items]
Total revenues	540	436	407
AmBisome \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	39	61	37
AmBisome \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	274	230	234
AmBisome \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	227	145	136
Letairis
Disaggregation of Revenue [Line Items]
Total revenues	206	314	618
Letairis \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	206	314	618
Letairis \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Letairis \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Ranexa
Disaggregation of Revenue [Line Items]
Total revenues	10	9	216
Ranexa \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	10	9	216
Ranexa \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Ranexa \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Zydelig
Disaggregation of Revenue [Line Items]
Total revenues	62	72	103
Zydelig \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	26	31	47
Zydelig \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	35	39	54
Zydelig \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	1	2	2
Other
Disaggregation of Revenue [Line Items]
Total revenues	209	195	203
Other \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	100	136	151
Other \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	80	45	43
Other \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	29	14	9
Royalty, contract and other revenues
Disaggregation of Revenue [Line Items]
Total revenues	297	334	330
Royalty, contract and other revenues \| U.S.
Disaggregation of Revenue [Line Items]
Total revenues	91	76	80
Royalty, contract and other revenues \| Europe
Disaggregation of Revenue [Line Items]
Total revenues	196	241	244
Royalty, contract and other revenues \| Other International
Disaggregation of Revenue [Line Items]
Total revenues	$ 10	$ 17	$ 6

Revenues - Disaggregation of Revenues (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2021

Dec. 31, 2020

Dec. 31, 2019

Disaggregation of Revenue [Line Items]

Total revenues

$ 27,305

$ 24,689

$ 22,449

U.S.

Disaggregation of Revenue [Line Items]