Investment Securities - Schedule of Amortized Cost and Fair Value of Investment Securities (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Investment securities available for sale
Investment securities available for sale, cost	$ 9,955	$ 9,967
Investment securities available for sale, gross unrealized gains	3	1
Investment securities available for sale, gross unrealized losses	(897)	(973)
Investment securities available for sale	9,061	8,995
Investment in marketable equity securities
Investment in marketable equity securities at cost	75	75
Investment in marketable equity, gross unrealized gains	14	21
Investment in marketable equity, gross unrealized losses	(4)	(1)
Investment in marketable equity, fair value	85	95
Investment securities held to maturity
Investment securities held to maturity, cost	10,381	10,279
Investment securities held to maturity, gross unrealized gains	3	0
Investment securities held to maturity, gross unrealized losses	(1,391)	(1,484)
Investment securities held to maturity, cost, fair value	8,993	8,795
Investments, Fair Value Disclosure [Abstract]
Total investment securities, amortized cost	20,411	20,321
Total investment securities, gross unrealized gains	20	22
Total investment securities, gross unrealized losses	(2,292)	(2,458)
Total investment securities, fair value	18,139	17,885
Investment securities available for sale, allowance for credit loss	4
U.S. Treasury
Investment securities available for sale
Investment securities available for sale, cost	2,091	2,035
Investment securities available for sale, gross unrealized gains	0	0
Investment securities available for sale, gross unrealized losses	(113)	(137)
Investment securities available for sale	1,978	1,898
Investment securities held to maturity
Investment securities held to maturity, cost	475	474
Investment securities held to maturity, gross unrealized gains	0	0
Investment securities held to maturity, gross unrealized losses	(42)	(50)
Investment securities held to maturity, cost, fair value	433	424
Government agency
Investment securities available for sale
Investment securities available for sale, cost	152	164
Investment securities available for sale, gross unrealized gains	0	0
Investment securities available for sale, gross unrealized losses	(2)	(2)
Investment securities available for sale	150	162
Investment securities held to maturity
Investment securities held to maturity, cost	1,550	1,548
Investment securities held to maturity, gross unrealized gains	0	0
Investment securities held to maturity, gross unrealized losses	(163)	(186)
Investment securities held to maturity, cost, fair value	1,387	1,362
Residential mortgage-backed securities
Investment securities available for sale
Investment securities available for sale, cost	5,415	5,424
Investment securities available for sale, gross unrealized gains	3	1
Investment securities available for sale, gross unrealized losses	(570)	(630)
Investment securities available for sale	4,848	4,795
Investment securities held to maturity
Investment securities held to maturity, cost	4,511	4,605
Investment securities held to maturity, gross unrealized gains	2	0
Investment securities held to maturity, gross unrealized losses	(655)	(723)
Investment securities held to maturity, cost, fair value	3,858	3,882
Commercial mortgage-backed securities
Investment securities available for sale
Investment securities available for sale, cost	1,755	1,774
Investment securities available for sale, gross unrealized gains	0	0
Investment securities available for sale, gross unrealized losses	(170)	(170)
Investment securities available for sale	1,585	1,604
Investment securities held to maturity
Investment securities held to maturity, cost	3,547	3,355
Investment securities held to maturity, gross unrealized gains	1	0
Investment securities held to maturity, gross unrealized losses	(497)	(484)
Investment securities held to maturity, cost, fair value	3,051	2,871
Corporate bonds
Investment securities available for sale
Investment securities available for sale, cost	542	570
Investment securities available for sale, gross unrealized gains	0	0
Investment securities available for sale, gross unrealized losses	(42)	(34)
Investment securities available for sale	500	536
Supranational securities
Investment securities held to maturity
Investment securities held to maturity, cost	296	295
Investment securities held to maturity, gross unrealized gains	0	0
Investment securities held to maturity, gross unrealized losses	(34)	(41)
Investment securities held to maturity, cost, fair value	262	254
Other
Investment securities held to maturity
Investment securities held to maturity, cost	2	2
Investment securities held to maturity, gross unrealized gains	0	0
Investment securities held to maturity, gross unrealized losses	0	0
Investment securities held to maturity, cost, fair value	$ 2	$ 2

Equity Securities FV-NI, Accumulated Gross Unrealized Gain, before Tax

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Equity Securities FV-NI, Accumulated Gross Unrealized Loss, before Tax

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Investments, Amortized Cost

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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 of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity).

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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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