Components of Other Comprehensive Income (Loss) - Schedule of Reclassification from AOCI (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and fees on loans and leases	$ 877		$ 492		$ 1,683	$ 936
Income tax expense	96		48		171	105
Other expense	52		57		96	95
Amounts reclassified from AOCI	(329)	$ (255)	(177)	$ (198)	(585)	(374)
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI	15		4		28	5
Reclassification out of Accumulated Other Comprehensive Income | Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and fees on loans and leases	17		4		32	3
Income tax expense	(4)		(1)		(8)	(1)
Amounts reclassified from AOCI	13		3		24	2
Reclassification out of Accumulated Other Comprehensive Income | Pension and Post-retirement Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax expense	0		(1)		(1)	(1)
Other expense	2		2		5	4
Amounts reclassified from AOCI	$ 2		$ 1		$ 4	$ 3