Investment Securities - Schedule of Unrealized Loss on Investments (Details) - USD ($)	Mar. 31, 2025	Dec. 31, 2024
Less than 12 months
Fair value	$ 1,369,000,000	$ 947,000,000
Unrealized loss	(14,000,000)	(22,000,000)
12 months or longer
Fair value	16,975,000,000	21,069,000,000
Unrealized loss	(3,434,000,000)	(4,383,000,000)
Credit reserves, available-for-sale	0	0
Credit reserves, held-to-maturity	0	0
U.S. Treasury and federal agencies
Less than 12 months
Fair value	0	0
Unrealized loss	0	0
12 months or longer
Fair value	595,000,000	1,873,000,000
Unrealized loss	(69,000,000)	(200,000,000)
U.S. States and political subdivisions
Less than 12 months
Fair value	43,000,000	87,000,000
Unrealized loss	(2,000,000)	(2,000,000)
12 months or longer
Fair value	495,000,000	472,000,000
Unrealized loss	(88,000,000)	(85,000,000)
Foreign government
Less than 12 months
Fair value	16,000,000	40,000,000
Unrealized loss	(1,000,000)	0
12 months or longer
Fair value	92,000,000	112,000,000
Unrealized loss	(2,000,000)	(5,000,000)
Agency mortgage-backed residential
Less than 12 months
Fair value	906,000,000	127,000,000
Unrealized loss	(4,000,000)	(3,000,000)
12 months or longer
Fair value	10,712,000,000	13,518,000,000
Unrealized loss	(2,407,000,000)	(3,109,000,000)
Mortgage-backed residential
Less than 12 months
Fair value	0	0
Unrealized loss	0	0
12 months or longer
Fair value	205,000,000	206,000,000
Unrealized loss	(40,000,000)	(43,000,000)
Agency mortgage-backed commercial
Less than 12 months
Fair value	217,000,000	428,000,000
Unrealized loss	(4,000,000)	(11,000,000)
12 months or longer
Fair value	3,534,000,000	3,445,000,000
Unrealized loss	(730,000,000)	(825,000,000)
Asset-backed
Less than 12 months
Fair value	0	0
Unrealized loss	0	0
12 months or longer
Fair value	71,000,000	124,000,000
Unrealized loss	(1,000,000)	(2,000,000)
Corporate debt
Less than 12 months
Fair value	187,000,000	265,000,000
Unrealized loss	(3,000,000)	(6,000,000)
12 months or longer
Fair value	1,271,000,000	1,319,000,000
Unrealized loss	$ (97,000,000)	$ (114,000,000)

Debt Securities, Available-for-Sale, Unrealized Loss Position, Long

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Amount excluding accrued interest, of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount, excluding accrued interest, of allowance for credit loss on investment in debt security measured at amortized cost (held-to-maturity).

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