SECURITIES - Schedule of Investments (Details) - USD ($) $ in Millions		Dec. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Fair Value	[1]	$ 32,765	$ 29,777
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Amortized Cost	[1]	8,599	9,184
Gross Unrealized Gains		1	9
Gross Unrealized Losses		(1,060)	(843)
Fair Value		7,540	8,350
Total equity securities, at cost, Amortized Cost		710	869
Equity securities, at cost, Fair Value		710	869
Equity securities, Amortized Cost		220	173
Equity securities, Fair Value		220	173
Portfolio level basis adjustments excluded from amortized cost		(75)	60
Debt Securities
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Amortized Cost		34,986	31,729
Gross Unrealized Gains		36	71
Gross Unrealized Losses		(2,257)	(2,023)
Fair Value		32,765	29,777
U.S. Treasury and other
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Amortized Cost		3,631	4,493
Gross Unrealized Gains		3	26
Gross Unrealized Losses		(109)	(139)
Fair Value		3,525	4,380
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		31,170	26,568
Gross Unrealized Gains		33	45
Gross Unrealized Losses		(2,148)	(1,881)
Fair Value		29,055	24,732
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Amortized Cost		8,187	8,696
Gross Unrealized Gains		0	9
Gross Unrealized Losses		(1,051)	(818)
Fair Value		7,136	7,887
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		30,897	26,289
Gross Unrealized Gains		33	45
Gross Unrealized Losses		(2,135)	(1,857)
Fair Value		28,795	24,477
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Amortized Cost		8,187	8,696
Gross Unrealized Gains		0	9
Gross Unrealized Losses		(1,051)	(818)
Fair Value		7,136	7,887
Other/non-agency
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Amortized Cost		273	279
Gross Unrealized Gains		0	0
Gross Unrealized Losses		(13)	(24)
Fair Value		260	255
Collateralized loan obligations
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Amortized Cost		184	667
Gross Unrealized Gains		0	0
Gross Unrealized Losses		0	(3)
Fair Value		184	664
Asset-backed securities
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Amortized Cost		412	488
Gross Unrealized Gains		1	0
Gross Unrealized Losses		(9)	(25)
Fair Value		$ 404	$ 463

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