Components of Other Comprehensive Income (Loss) - Schedule of Reclassification from AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Interest and fees on loans and leases	$ 3,575	$ 2,292	$ 1,957
Income tax expense	212	247	274
Other expense	182	186	169
Amounts reclassified from AOCI	(916)	(912)	(1,010)
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Amounts reclassified from AOCI	59	23	1
Reclassification out of Accumulated Other Comprehensive Income | Cash Flow Hedges
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Interest and fees on loans and leases	69	20	(9)
Income tax expense	(17)	(5)	2
Amounts reclassified from AOCI	52	15	(7)
Reclassification out of Accumulated Other Comprehensive Income | Pension and Post-retirement Plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Income tax expense	(2)	(2)	(2)
Other expense	9	10	10
Amounts reclassified from AOCI	$ 7	$ 8	$ 8