Securities - Schedule of Details of Securities (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
SECURITIES AVAILABLE FOR SALE
Amortized Cost	$ 43,005	$ 42,695
Gross Unrealized Gains	7	10
Gross Unrealized Losses	5,714	5,520
Fair Value	37,298	37,185
HELD-TO-MATURITY SECURITIES
Total	8,272	8,575
Gross Unrealized Gains	2	10
Gross Unrealized Losses	594	529
Fair Value	7,680	8,056
Debt securities, available for sale, accrued interest	69	64
Debt securities, held to maturity, accrued interest	24	25
U.S. Treasury, agencies and corporations
SECURITIES AVAILABLE FOR SALE
Amortized Cost	9,354	9,300
Gross Unrealized Gains	1	6
Gross Unrealized Losses	213	280
Fair Value	9,142	9,026
Agency residential collateralized mortgage obligations
SECURITIES AVAILABLE FOR SALE
Amortized Cost	19,285	18,911
Gross Unrealized Gains	6	4
Gross Unrealized Losses	3,575	3,437
Fair Value	15,716	15,478
HELD-TO-MATURITY SECURITIES
Total	5,025	5,170
Gross Unrealized Gains	2	9
Gross Unrealized Losses	341	283
Fair Value	4,686	4,896
Agency residential mortgage-backed securities
SECURITIES AVAILABLE FOR SALE
Amortized Cost	4,090	4,189
Gross Unrealized Gains	0	0
Gross Unrealized Losses	639	600
Fair Value	3,451	3,589
HELD-TO-MATURITY SECURITIES
Total	162	165
Gross Unrealized Gains	0	0
Gross Unrealized Losses	17	13
Fair Value	145	152
Agency commercial mortgage-backed securities
SECURITIES AVAILABLE FOR SALE
Amortized Cost	10,276	10,295
Gross Unrealized Gains	0	0
Gross Unrealized Losses	1,287	1,203
Fair Value	8,989	9,092
HELD-TO-MATURITY SECURITIES
Total	2,448	2,473
Gross Unrealized Gains	0	1
Gross Unrealized Losses	216	204
Fair Value	2,232	2,270
Asset-backed securities
HELD-TO-MATURITY SECURITIES
Total	611	738
Gross Unrealized Gains	0	0
Gross Unrealized Losses	19	29
Fair Value	592	709
Debt securities, held-to-maturity, purchase of senior notes	606	731
Other securities
HELD-TO-MATURITY SECURITIES
Total	26	29
Gross Unrealized Gains	0	0
Gross Unrealized Losses	1	0
Fair Value	$ 25	$ 29

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