INTANGIBLE ASSETS - Summary of Intangible Assets (Details) - USD ($) $ in Millions	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023
Finite-Lived Intangible Assets [Line Items]
Gross  Carrying Amount	$ 31,819		$ 31,819
Accumulated Amortization	(13,628)		(12,436)
Foreign Currency Translation Adjustment	1		1
Net Carrying Amount	18,192		19,384
Indefinite-lived Intangible Assets (Excluding Goodwill) [Abstract]
Gross  Carrying Amount	4,640		7,070
Foreign Currency Translation Adjustment	0		0
Net Carrying Amount	4,640		7,070
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Gross  Carrying Amount	36,459		38,889
Accumulated Amortization	(13,628)		(12,436)
Foreign Currency Translation Adjustment	1		1
Net Carrying Amount	22,832		26,454
In Process Research And Development NSCLC
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Indefinite-lived intangible assets, fair value		$ 3,500	5,900
In Process Research And Development Bulevirtide
Indefinite-lived Intangible Assets (Excluding Goodwill) [Abstract]
Gross  Carrying Amount			1,100
Intangible asset – sofosbuvir
Finite-Lived Intangible Assets [Line Items]
Gross  Carrying Amount	10,720		10,720
Accumulated Amortization	(7,399)		(7,050)
Foreign Currency Translation Adjustment	0		0
Net Carrying Amount	3,321		3,670
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Accumulated Amortization	(7,399)		(7,050)
Intangible asset – axicabtagene ciloleucel
Finite-Lived Intangible Assets [Line Items]
Gross  Carrying Amount	7,110		7,110
Accumulated Amortization	(2,517)		(2,314)
Foreign Currency Translation Adjustment	0		0
Net Carrying Amount	4,593		4,796
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Accumulated Amortization	(2,517)		(2,314)
Intangible asset – Trodelvy
Finite-Lived Intangible Assets [Line Items]
Gross  Carrying Amount	11,730		11,730
Accumulated Amortization	(2,543)		(2,002)
Foreign Currency Translation Adjustment	0		0
Net Carrying Amount	9,187		9,728
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Accumulated Amortization	(2,543)		(2,002)
Intangible asset – Hepcludex
Finite-Lived Intangible Assets [Line Items]
Gross  Carrying Amount	845		845
Accumulated Amortization	(286)		(243)
Foreign Currency Translation Adjustment	0		0
Net Carrying Amount	559		602
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Accumulated Amortization	(286)		(243)
Other
Finite-Lived Intangible Assets [Line Items]
Gross  Carrying Amount	1,414		1,414
Accumulated Amortization	(883)		(827)
Foreign Currency Translation Adjustment	1		1
Net Carrying Amount	533		588
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Accumulated Amortization	$ (883)		$ (827)