Loans, Leases, and Allowance for Credit Losses (Summary of Changes in the Allowance for Credit Losses) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Allowance for loan losses
Balance at beginning of period	$ 478	$ 646	$ 513	$ 777
Provision for loan and lease losses	39	(113)	10	(236)
Gross loan and lease charge-offs	18	8	35	29
Recoveries	9	10	20	23
Net loan and lease charge-offs (recoveries)	9	(2)	15	6
Balance at end of period	508	535	508	535
Reserve for unfunded lending commitments
Balance at beginning of period	36	49	40	58
Provision for unfunded lending commitments	2	(10)	(2)	(19)
Balance at end of period	38	39	38	39
Total allowance for credit losses	546	574	546	574
Commercial
Allowance for loan losses
Balance at beginning of period	282	362	311	464
Provision for loan and lease losses	12	(43)	(12)	(137)
Gross loan and lease charge-offs	15	5	28	23
Recoveries	7	7	15	17
Net loan and lease charge-offs (recoveries)	8	(2)	13	6
Balance at end of period	286	321	286	321
Reserve for unfunded lending commitments
Balance at beginning of period	14	24	19	30
Provision for unfunded lending commitments	(1)	(3)	(6)	(9)
Balance at end of period	13	21	13	21
Total allowance for credit losses	299	342	299	342
Commercial real estate
Allowance for loan losses
Balance at beginning of period	102	152	107	171
Provision for loan and lease losses	12	(41)	7	(60)
Gross loan and lease charge-offs	0	0	0	0
Recoveries	0	0	0	0
Net loan and lease charge-offs (recoveries)	0	0	0	0
Balance at end of period	114	111	114	111
Reserve for unfunded lending commitments
Balance at beginning of period	12	17	11	20
Provision for unfunded lending commitments	3	(7)	4	(10)
Balance at end of period	15	10	15	10
Total allowance for credit losses	129	121	129	121
Consumer
Allowance for loan losses
Balance at beginning of period	94	132	95	142
Provision for loan and lease losses	15	(29)	15	(39)
Gross loan and lease charge-offs	3	3	7	6
Recoveries	2	3	5	6
Net loan and lease charge-offs (recoveries)	1	0	2	0
Balance at end of period	108	103	108	103
Reserve for unfunded lending commitments
Balance at beginning of period	10	8	10	8
Provision for unfunded lending commitments	0	0	0	0
Balance at end of period	10	8	10	8
Total allowance for credit losses	$ 118	$ 111	$ 118	$ 111