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, 2021	Dec. 31, 2020	Dec. 31, 2019
Allowance for loan and lease losses
Balance at beginning of period	$ 777	$ 497
Provision for loan losses	(258)	385	$ 37
Gross loan and lease charge-offs	48	128
Recoveries	42	23
Net loan and lease charge-offs (recoveries)	6	105
Balance at ending of period	513	777	497
Reserve for unfunded lending commitments
Balance at beginning of period	58	29
Provision for unfunded lending commitments	(18)	29	2
Balance at end of period	40	58	29
Total allowance for credit losses	553	835
Commercial
Allowance for loan and lease losses
Balance at beginning of period	464	282
Provision for loan losses	(147)	281
Gross loan and lease charge-offs	35	113
Recoveries	29	14
Net loan and lease charge-offs (recoveries)	6	99
Balance at ending of period	311	464	282
Reserve for unfunded lending commitments
Balance at beginning of period	30	11
Provision for unfunded lending commitments	(11)	19
Balance at end of period	19	30	11
Total allowance for credit losses	330	494
Commercial real estate
Allowance for loan and lease losses
Balance at beginning of period	171	69
Provision for loan losses	(67)	103
Gross loan and lease charge-offs	0	1
Recoveries	3	0
Net loan and lease charge-offs (recoveries)	(3)	1
Balance at ending of period	107	171	69
Reserve for unfunded lending commitments
Balance at beginning of period	20	12
Provision for unfunded lending commitments	(9)	8
Balance at end of period	11	20	12
Total allowance for credit losses	118	191
Consumer
Allowance for loan and lease losses
Balance at beginning of period	142	146
Provision for loan losses	(44)	1
Gross loan and lease charge-offs	13	14
Recoveries	10	9
Net loan and lease charge-offs (recoveries)	3	5
Balance at ending of period	95	142	146
Reserve for unfunded lending commitments
Balance at beginning of period	8	6
Provision for unfunded lending commitments	2	2
Balance at end of period	10	8	$ 6
Total allowance for credit losses	$ 105	$ 150