Components of Other Comprehensive Income (Loss) - Schedule of Reclassification from AOCI (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2024
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and fees on loans and leases	$ (921)		$ (975)		$ (1,816)	$ (1,927)
Income tax expense	64		56		127	113
Other expense	38		46		82	86
Total reclassification from AOCI	(245)	$ (222)	(204)	$ (197)	(467)	(401)
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total reclassification from AOCI	11		15		22	30
Reclassification out of Accumulated Other Comprehensive Income | Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and fees on loans and leases	12		17		24	34
Income tax expense	(3)		(4)		(6)	(8)
Total reclassification from AOCI	9		13		18	26
Reclassification out of Accumulated Other Comprehensive Income | Pension and Post-retirement Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax expense	(1)		(1)		(2)	(2)
Other expense	3		3		6	6
Total reclassification from AOCI	$ 2		$ 2		$ 4	$ 4