Investment Securities - Schedule of Investment Securities Maturity Information (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Investment securities available for sale
Non-amortizing securities maturing in one year or less, cost	$ 34	$ 37
Non-amortizing securities maturing in after one through five years, cost	2,120	2,068
Non-amortizing securities maturing in after five through 10 years, cost	463	483
Non-amortizing securities maturing in after 10 years, cost	16	17
Investment securities available for sale, cost	9,955	9,967
Non-amortizing securities maturing in one year or less, fair value	33	37
Non-amortizing securities maturing in after one through five years, fair value	2,004	1,928
Non-amortizing securities maturing in after five through 10 years, fair value	427	455
Non-amortizing securities maturing in after 10 years, fair value	14	14
Investment securities available for sale, fair value	9,061	8,995
Investment securities held to maturity
Non-amortizing securities maturing in one year or less, cost	51	51
Non-amortizing securities maturing in after one through five years, cost	1,579	1,479
Non-amortizing securities maturing in after five through 10 years, cost	693	789
Investment securities held to maturity, cost	10,381	10,279
Non-amortizing securities maturing in one year or less, fair value	51	51
Non-amortizing securities maturing in after one through five years, fair value	1,440	1,328
Non-amortizing securities maturing in after five through 10 years, fair value	593	663
Investment securities held to maturity, cost, fair value	8,993	8,795
Investment securities available for sale, allowance for credit loss	4
Government agency
Investment securities available for sale
Without single maturity date, cost	152	164
Without single maturity date, fair value	150	162
Residential mortgage-backed securities
Investment securities available for sale
Without single maturity date, cost	5,415	5,424
Without single maturity date, fair value	4,848	4,795
Investment securities held to maturity
Without single maturity date, cost	4,511	4,605
Without single maturity date, fair value	3,858	3,882
Commercial mortgage-backed securities
Investment securities available for sale
Without single maturity date, cost	1,755	1,774
Without single maturity date, fair value	1,585	1,604
Investment securities held to maturity
Without single maturity date, cost	3,547	3,355
Without single maturity date, fair value	$ 3,051	$ 2,871