Investment Securities - Schedule of Amortized Cost and Fair Value by Contractual Maturity (Details) - USD ($) $ in Millions	Dec. 31, 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	1,270
Total	1,270
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	1,083
Fair Value	1,083	$ 1,161
Amortized Cost
Within 1 year	24
After 1 year through 5 years	76
After 5 years through 10 years	270
After 10 years	1,258
Subtotal	1,628
Government agency issued MBS and CMO	7,302
Securities available for sale, amortized cost	8,930
Fair Value
Within 1 year	24
After 1 year through 5 years	71
After 5 years through 10 years	241
After 10 years	1,091
Subtotal	1,427
Government agency issued MBS and CMO	6,469
Securities available-for-sale	$ 7,896	$ 8,391