Components of Other Comprehensive Income (Loss) - Schedule of Reclassification from AOCI (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and fees on loans and leases	$ (885)	$ (895)
Income tax expense	76	63
Other expense	60	61
Total reclassification from AOCI	(266)	(222)
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total reclassification from AOCI	8	11
Reclassification out of Accumulated Other Comprehensive Income | Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and fees on loans and leases	8	12
Income tax expense	(2)	(3)
Total reclassification from AOCI	6	9
Reclassification out of Accumulated Other Comprehensive Income | Pension and Post-retirement Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax expense	(1)	(1)
Other expense	3	3
Total reclassification from AOCI	$ 2	$ 2