Investment Securities - Schedule of Investment Securities Maturity Information (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Investment securities available for sale
Non-amortizing securities maturing in one year or less, cost	$ 48	$ 0
Non-amortizing securities maturing in after one through five years, cost	2,063	2,049
Non-amortizing securities maturing in after five through 10 years, cost	503	523
Non-amortizing securities maturing in after 10 years, cost	16	17
Investment securities available for sale, cost	10,083	9,215
Non-amortizing securities maturing in one year or less, fair value	48	0
Non-amortizing securities maturing in after one through five years, fair value	1,914	2,048
Non-amortizing securities maturing in after five through 10 years, fair value	481	548
Non-amortizing securities maturing in after 10 years, fair value	15	17
Investment securities available for sale, fair value	9,088	9,203
Investment securities held to maturity
Non-amortizing securities maturing in one year or less, cost	53	2
Non-amortizing securities maturing in after one through five years, cost	1,334	0
Non-amortizing securities maturing in after five through 10 years, cost	930	0
Investment securities held to maturity, cost	9,661	3,809
Non-amortizing securities maturing in one year or less, fair value	51	2
Non-amortizing securities maturing in after one through five years, fair value	1,190	0
Non-amortizing securities maturing in after five through 10 years, fair value	783	0
Investment securities held to maturity, cost, fair value	8,166	3,759
Government agency
Investment securities available for sale
Without single maturity date, cost	175	221
Without single maturity date, fair value	173	221
Residential mortgage-backed securities
Investment securities available for sale
Without single maturity date, cost	5,450	4,757
Without single maturity date, fair value	4,784	4,729
Investment securities held to maturity
Without single maturity date, cost	4,510	2,322
Without single maturity date, fair value	3,745	2,306
Commercial mortgage-backed securities
Investment securities available for sale
Without single maturity date, cost	1,828	1,648
Without single maturity date, fair value	1,673	1,640
Investment securities held to maturity
Without single maturity date, cost	2,834	1,485
Without single maturity date, fair value	$ 2,397	$ 1,451