SECURITIES - Schedule of Investments (Details) - USD ($) $ in Millions		Mar. 31, 2025	Dec. 31, 2024
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Fair Value	[1]	$ 34,208	$ 32,765
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Amortized Cost	[1]	8,469	8,599
Gross Unrealized Gains		0	1
Gross Unrealized Gains		(954)	(1,060)
Fair Value		7,515	7,540
Total equity securities, at cost, Amortized Cost		711	710
Equity securities, at cost, fair value		711	710
Equity Securities, Amortized Cost		236	220
Equity Securities, Fair Value		236	220
Portfolio level basis adjustments excluded from amortized cost		(2)	(75)
Total debt securities available for sale, at fair value
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Amortized Cost		35,986	34,986
Gross Unrealized Gains		96	36
Gross Unrealized Losses		(1,874)	(2,257)
Fair Value		34,208	32,765
U.S. Treasury and other
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Amortized Cost		4,145	3,631
Gross Unrealized Gains		15	3
Gross Unrealized Losses		(91)	(109)
Fair Value		4,069	3,525
State and political subdivisions
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Amortized Cost		1	1
Gross Unrealized Gains		0	0
Gross Unrealized Losses		0	0
Fair Value		1	1
Total mortgage-backed securities
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Amortized Cost		31,716	31,170
Gross Unrealized Gains		81	33
Gross Unrealized Losses		(1,783)	(2,148)
Fair Value		30,014	29,055
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Amortized Cost		8,077	8,187
Gross Unrealized Gains		0	0
Gross Unrealized Gains		(948)	(1,051)
Fair Value		7,129	7,136
Federal agencies and U.S. government sponsored entities
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Amortized Cost		31,444	30,897
Gross Unrealized Gains		81	33
Gross Unrealized Losses		(1,772)	(2,135)
Fair Value		29,753	28,795
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Amortized Cost		8,077	8,187
Gross Unrealized Gains		0	0
Gross Unrealized Gains		(948)	(1,051)
Fair Value		7,129	7,136
Other/non-agency
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Amortized Cost		272	273
Gross Unrealized Gains		0	0
Gross Unrealized Losses		(11)	(13)
Fair Value		261	260
Collateralized loan obligations
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Amortized Cost		124	184
Gross Unrealized Gains		0	0
Gross Unrealized Losses		0	0
Fair Value		124	184
Asset-backed securities
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Amortized Cost		392	412
Gross Unrealized Gains		0	1
Gross Unrealized Gains		(6)	(9)
Fair Value		$ 386	$ 404

[1] Includes only collateral pledged by the Company where counterparties have the right to sell or pledge the collateral.