Fair Value Measurements - Schedule of Change in Fair Values of Level 3 Financial Instruments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning of Period Balance	$ 3	$ 2	$ 2	$ 2
Gains (Losses) Included in Other Comprehensive Income	0	0	0	0
Gains (Losses) Included in Earnings	(1)	1	0	1
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	0	0	0	0
Transfers Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
End of Period Balance	2	3	2	3
Unrealized Gains (Losses) Included in Earnings	0	0	0	0
Interest rate
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning of Period Balance	2	(2)	(4)	(2)
Gains (Losses) Included in Other Comprehensive Income	0	0	0	0
Gains (Losses) Included in Earnings	1	2	10	(5)
Purchases	2	6	8	7
Sales	0	0	0	0
Settlements	0	0	0	0
Transfers Other	0	0	0	0
Transfers into Level 3	0	1	(5)	2
Transfers out of Level 3	(2)	0	(6)	5
End of Period Balance	3	7	3	7
Unrealized Gains (Losses) Included in Earnings	0	0	0	0
Other
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning of Period Balance	2	1	0	2
Gains (Losses) Included in Other Comprehensive Income	0	0	0	0
Gains (Losses) Included in Earnings	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	0	0	0	0
Transfers Other	(1)	0	1	(1)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
End of Period Balance	1	1	1	1
Unrealized Gains (Losses) Included in Earnings	0	0	0	0
Loans, net of unearned income (residential)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning of Period Balance	11	11	10	9
Gains (Losses) Included in Other Comprehensive Income	0	0	0	0
Gains (Losses) Included in Earnings	0	0	1	0
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	0	0	0	0
Transfers Other	(1)	(2)	(1)	(2)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	2
End of Period Balance	10	9	10	9
Unrealized Gains (Losses) Included in Earnings	$ 0	$ 0	$ 0	$ 0