Investment Securities - Schedule of Amortized Cost and Fair Value by Contractual Maturity (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
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	1,297
Total	1,297
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	1,108
Fair Value	1,108	$ 1,161
Amortized Cost
Within 1 year	44
After 1 year through 5 years	137
After 5 years through 10 years	369
After 10 years	1,340
Subtotal	1,890
Government agency issued MBS and CMO	7,226
Securities available for sale, amortized cost	9,116
Fair Value
Within 1 year	44
After 1 year through 5 years	127
After 5 years through 10 years	332
After 10 years	1,170
Subtotal	1,673
Government agency issued MBS and CMO	6,251
Securities available-for-sale	$ 7,924	$ 8,391