INTANGIBLE ASSETS - Summary of Intangible Assets (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Finite-Lived Intangible Assets [Line Items]
Gross  Carrying Amount	$ 31,819	$ 31,819
Accumulated Amortization	(13,032)	(12,436)
Foreign Currency Translation Adjustment	1	1
Net Carrying Amount	18,788	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	(13,032)	(12,436)
Foreign Currency Translation Adjustment	1	1
Net Carrying Amount	23,428	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 Bulveritide
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	(7,224)	(7,050)
Foreign Currency Translation Adjustment	0	0
Net Carrying Amount	3,496	3,670
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Accumulated Amortization	(7,224)	(7,050)
Intangible asset – axicabtagene ciloleucel
Finite-Lived Intangible Assets [Line Items]
Gross  Carrying Amount	7,110	7,110
Accumulated Amortization	(2,416)	(2,314)
Foreign Currency Translation Adjustment	0	0
Net Carrying Amount	4,694	4,796
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Accumulated Amortization	(2,416)	(2,314)
Intangible asset – Trodelvy
Finite-Lived Intangible Assets [Line Items]
Gross  Carrying Amount	11,730	11,730
Accumulated Amortization	(2,272)	(2,002)
Foreign Currency Translation Adjustment	0	0
Net Carrying Amount	9,458	9,728
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Accumulated Amortization	(2,272)	(2,002)
Intangible asset – Hepcludex
Finite-Lived Intangible Assets [Line Items]
Gross  Carrying Amount	845	845
Accumulated Amortization	(265)	(243)
Foreign Currency Translation Adjustment	0	0
Net Carrying Amount	580	602
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Accumulated Amortization	(265)	(243)
Other
Finite-Lived Intangible Assets [Line Items]
Gross  Carrying Amount	1,414	1,414
Accumulated Amortization	(855)	(827)
Foreign Currency Translation Adjustment	1	1
Net Carrying Amount	560	588
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Accumulated Amortization	$ (855)	$ (827)