INVESTMENT SECURITIES - Securities Classified as Current and Long-Term (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Investment Securities, Available-for-sale Amortized Cost to Fair Value
Amortized Cost	$ 18,485	$ 18,302
Gross Unrealized Gains	27	34
Gross Unrealized Losses	(1,435)	(1,328)
Fair Value	17,077	17,008
U.S. Treasury and agency obligations
Investment Securities, Available-for-sale Amortized Cost to Fair Value
Amortized Cost	2,928	2,717
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(84)	(51)
Fair Value	2,844	2,667
Mortgage-backed securities
Investment Securities, Available-for-sale Amortized Cost to Fair Value
Amortized Cost	3,925	3,946
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(486)	(425)
Fair Value	3,439	3,522
Tax-exempt municipal securities
Investment Securities, Available-for-sale Amortized Cost to Fair Value
Amortized Cost	850	879
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(24)	(22)
Fair Value	826	858
Residential
Investment Securities, Available-for-sale Amortized Cost to Fair Value
Amortized Cost	462	465
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(68)	(66)
Fair Value	394	400
Commercial
Investment Securities, Available-for-sale Amortized Cost to Fair Value
Amortized Cost	1,420	1,471
Gross Unrealized Gains	1	0
Gross Unrealized Losses	(113)	(126)
Fair Value	1,308	1,345
Asset-backed securities
Investment Securities, Available-for-sale Amortized Cost to Fair Value
Amortized Cost	1,552	1,813
Gross Unrealized Gains	2	2
Gross Unrealized Losses	(37)	(44)
Fair Value	1,517	1,771
Corporate debt securities
Investment Securities, Available-for-sale Amortized Cost to Fair Value
Amortized Cost	7,348	7,011
Gross Unrealized Gains	24	28
Gross Unrealized Losses	(623)	(594)
Fair Value	$ 6,749	$ 6,445

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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