Investment Securities - Schedule Of Amortized Cost And Fair Value By Contractual Maturity (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Amortized Cost
Within 1 year	$ 0
After 1 year through 5 years	0
After 5 years through 10 years	0
After 10 years	0
Subtotal	0
Government agency issued MBS and CMO	1,335
Total	1,335
Fair Value
Within 1 year	0
After 1 year through 5 years	0
After 5 years through 10 years	0
After 10 years	0
Subtotal	0
Government agency issued MBS and CMO	1,104
Fair Value	1,104	$ 1,209
Amortized Cost
Within 1 year	14
After 1 year through 5 years	125
After 5 years through 10 years	394
After 10 years	1,431
Subtotal	1,964
Government agency issued MBS and CMO	7,684
Securities available for sale, amortized cost	9,648
Fair Value
Within 1 year	14
After 1 year through 5 years	118
After 5 years through 10 years	341
After 10 years	1,202
Subtotal	1,675
Government agency issued MBS and CMO	6,425
Securities available-for-sale	$ 8,100	$ 8,836