Components of Other Comprehensive Income (Loss) - Schedule of Reclassification from AOCI (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and fees on loans and leases	$ 895	$ 952
Income tax expense	63	57
Other expense	45	43
Total reclassification from AOCI	(222)	(197)
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total reclassification from AOCI	11	15
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
Income tax expense	(3)	(4)
Total reclassification from AOCI	9	13
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