Loans, Leases, and Allowance for Credit Losses (Summary of Changes in the Allowance for Credit Losses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Allowance for loan and lease losses
Balance at beginning of period	$ 513	$ 777
Provision for loan losses	101	(258)	$ 385
Gross loan and lease charge-offs	82	48
Recoveries	43	42
Net loan and lease charge-offs (recoveries)	39	6
Balance at ending of period	575	513	777
Reserve for unfunded lending commitments
Balance at beginning of period	40	58
Provision for unfunded lending commitments	21	(18)	29
Balance at end of period	61	40	58
Total allowance for credit losses	636	553
Commercial
Allowance for loan and lease losses
Balance at beginning of period	311	464
Provision for loan losses	29	(147)
Gross loan and lease charge-offs	72	35
Recoveries	32	29
Net loan and lease charge-offs (recoveries)	40	6
Balance at ending of period	300	311	464
Reserve for unfunded lending commitments
Balance at beginning of period	19	30
Provision for unfunded lending commitments	(3)	(11)
Balance at end of period	16	19	30
Total allowance for credit losses	316	330
Commercial real estate
Allowance for loan and lease losses
Balance at beginning of period	107	171
Provision for loan losses	49	(67)
Gross loan and lease charge-offs	0	0
Recoveries	0	3
Net loan and lease charge-offs (recoveries)	0	(3)
Balance at ending of period	156	107	171
Reserve for unfunded lending commitments
Balance at beginning of period	11	20
Provision for unfunded lending commitments	22	(9)
Balance at end of period	33	11	20
Total allowance for credit losses	189	118
Consumer
Allowance for loan and lease losses
Balance at beginning of period	95	142
Provision for loan losses	23	(44)
Gross loan and lease charge-offs	10	13
Recoveries	11	10
Net loan and lease charge-offs (recoveries)	(1)	3
Balance at ending of period	119	95	142
Reserve for unfunded lending commitments
Balance at beginning of period	10	8
Provision for unfunded lending commitments	2	2
Balance at end of period	12	10	$ 8
Total allowance for credit losses	$ 131	$ 105