Investment Securities - Schedule of Investment Securities Maturity Information (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Investment securities available for sale
Non-amortizing securities maturing in one year or less, cost	$ 2,987	$ 37
Non-amortizing securities maturing in after one through five years, cost	1,910	2,068
Non-amortizing securities maturing in after five through 10 years, cost	510	483
Non-amortizing securities maturing in after 10 years, cost	154	17
Investment securities available for sale, cost	12,923	9,967
Non-amortizing securities maturing in one year or less, fair value	2,975	37
Non-amortizing securities maturing in after one through five years, fair value	1,787	1,928
Non-amortizing securities maturing in after five through 10 years, fair value	457	455
Non-amortizing securities maturing in after 10 years, fair value	148	14
Investment securities available for sale, fair value	11,894	8,995
Investment securities held to maturity
Non-amortizing securities maturing in one year or less, cost	2	51
Non-amortizing securities maturing in after one through five years, cost	1,581	1,479
Non-amortizing securities maturing in after five through 10 years, cost	694	789
Investment securities held to maturity, cost	10,201	10,279
Non-amortizing securities maturing in one year or less, fair value	2	51
Non-amortizing securities maturing in after one through five years, fair value	1,426	1,328
Non-amortizing securities maturing in after five through 10 years, fair value	585	663
Investment securities held to maturity, cost, fair value	8,652	8,795
Investment securities available for sale, allowance for credit loss	3
Government agency
Investment securities available for sale
Without single maturity date, cost	143	164
Without single maturity date, fair value	140	162
Residential mortgage-backed securities
Investment securities available for sale
Without single maturity date, cost	5,443	5,424
Without single maturity date, fair value	4,810	4,795
Investment securities held to maturity
Without single maturity date, cost	4,406	4,605
Without single maturity date, fair value	3,716	3,882
Commercial mortgage-backed securities
Investment securities available for sale
Without single maturity date, cost	1,776	1,774
Without single maturity date, fair value	1,577	1,604
Investment securities held to maturity
Without single maturity date, cost	3,518	3,355
Without single maturity date, fair value	$ 2,923	$ 2,871