Loans, Leases, and Allowance for Credit Losses (Summary of Outstanding Loan Balances (Accruing And Nonaccruing) Categorized By Credit Quality Indicators) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	$ 12,539	$ 15,931
2020	8,182	9,700
2019	5,938	7,093
2018	3,865	4,439
2017	2,776	3,104
Prior	5,654	5,596
Revolving loans amortized cost basis	11,327	7,321
Revolving loans converted to term loans amortized cost basis	570	292
Total loans	50,851	53,476
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	7,717	11,233
2020	4,350	5,348
2019	3,022	3,934
2018	2,087	2,437
2017	1,503	1,087
Prior	2,414	2,526
Revolving loans amortized cost basis	7,132	3,766
Revolving loans converted to term loans amortized cost basis	215	141
Total loans	28,440	30,472
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	3,078	3,260
2020	2,553	2,992
2019	2,094	2,190
2018	1,255	876
2017	575	821
Prior	1,505	1,436
Revolving loans amortized cost basis	889	501
Revolving loans converted to term loans amortized cost basis	249	28
Total loans	12,198	12,104
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	1,744	1,438
2020	1,279	1,360
2019	822	969
2018	523	1,126
2017	698	1,196
Prior	1,735	1,634
Revolving loans amortized cost basis	3,306	3,054
Revolving loans converted to term loans amortized cost basis	106	123
Total loans	10,213	10,900
Commercial and industrial \| Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	2,607	2,844
2020	1,358	3,054
2019	1,293	2,225
2018	816	979
2017	387	328
Prior	328	303
Revolving loans amortized cost basis	6,935	3,585
Revolving loans converted to term loans amortized cost basis	143	126
Total loans	13,867	13,444
PPP \| Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	1,317	5,572
2020	538	0
2019	0	0
2018	0	0
2017	0	0
Prior	0	0
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	1,855	5,572
Leasing \| Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	46	90
2020	75	122
2019	74	47
2018	65	36
2017	43	14
Prior	24	11
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	327	320
Owner-occupied \| Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	2,444	1,696
2020	1,407	1,345
2019	1,102	1,303
2018	956	1,003
2017	746	677
Prior	1,812	1,968
Revolving loans amortized cost basis	194	178
Revolving loans converted to term loans amortized cost basis	72	15
Total loans	8,733	8,185
Municipal \| Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	1,303	1,031
2020	972	827
2019	553	359
2018	250	419
2017	327	68
Prior	250	244
Revolving loans amortized cost basis	3	3
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	3,658	2,951
Construction and land development \| Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	640	582
2020	739	1,006
2019	544	278
2018	94	41
2017	24	1
Prior	2	6
Revolving loans amortized cost basis	650	428
Revolving loans converted to term loans amortized cost basis	64	3
Total loans	2,757	2,345
Term \| Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	2,438	2,678
2020	1,814	1,986
2019	1,550	1,912
2018	1,161	835
2017	551	820
Prior	1,503	1,430
Revolving loans amortized cost basis	239	73
Revolving loans converted to term loans amortized cost basis	185	25
Total loans	9,441	9,759
Home equity credit line \| Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior	0	0
Revolving loans amortized cost basis	2,913	2,625
Revolving loans converted to term loans amortized cost basis	103	120
Total loans	3,016	2,745
1-4 family residential \| Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	1,391	1,187
2020	1,024	1,029
2019	732	841
2018	487	1,100
2017	690	1,191
Prior	1,726	1,621
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	6,050	6,969
Construction and other consumer real estate \| Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	295	200
2020	232	296
2019	73	106
2018	27	16
2017	4	1
Prior	7	11
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	638	630
Bankcard and other revolving plans \| Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior	0	0
Revolving loans amortized cost basis	393	429
Revolving loans converted to term loans amortized cost basis	3	3
Total loans	396	432
Other \| Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	58	51
2020	23	35
2019	17	22
2018	9	10
2017	4	4
Prior	2	2
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	113	124
Pass \| Commercial and industrial \| Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	2,561	2,585
2020	1,309	2,743
2019	1,179	1,903
2018	748	829
2017	354	296
Prior	239	228
Revolving loans amortized cost basis	6,594	3,298
Revolving loans converted to term loans amortized cost basis	121	109
Total loans	13,105	11,991
Pass \| PPP \| Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	1,317	5,572
2020	535	0
2019	0	0
2018	0	0
2017	0	0
Prior	0	0
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	1,852	5,572
Pass \| Leasing \| Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	46	87
2020	74	121
2019	70	44
2018	64	34
2017	42	14
Prior	19	5
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	315	305
Pass \| Owner-occupied \| Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	2,420	1,588
2020	1,366	1,205
2019	1,028	1,167
2018	868	895
2017	695	585
Prior	1,663	1,806
Revolving loans amortized cost basis	177	161
Revolving loans converted to term loans amortized cost basis	69	11
Total loans	8,286	7,418
Pass \| Municipal \| Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	1,303	1,031
2020	963	827
2019	553	359
2018	250	419
2017	327	68
Prior	220	227
Revolving loans amortized cost basis	3	3
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	3,619	2,934
Pass \| Construction and land development \| Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	640	558
2020	736	933
2019	515	267
2018	94	41
2017	24	1
Prior	2	6
Revolving loans amortized cost basis	650	423
Revolving loans converted to term loans amortized cost basis	64	3
Total loans	2,725	2,232
Pass \| Term \| Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	2,407	2,524
2020	1,765	1,858
2019	1,491	1,639
2018	1,066	761
2017	529	778
Prior	1,401	1,291
Revolving loans amortized cost basis	239	73
Revolving loans converted to term loans amortized cost basis	179	20
Total loans	9,077	8,944
Pass \| Home equity credit line \| Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior	0	0
Revolving loans amortized cost basis	2,903	2,606
Revolving loans converted to term loans amortized cost basis	96	115
Total loans	2,999	2,721
Pass \| 1-4 family residential \| Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	1,391	1,185
2020	1,021	1,017
2019	728	833
2018	484	1,081
2017	681	1,174
Prior	1,691	1,570
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	5,996	6,860
Pass \| Construction and other consumer real estate \| Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	295	200
2020	232	296
2019	73	106
2018	27	16
2017	4	1
Prior	7	11
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	638	630
Pass \| Bankcard and other revolving plans \| Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior	0	0
Revolving loans amortized cost basis	391	426
Revolving loans converted to term loans amortized cost basis	3	2
Total loans	394	428
Pass \| Other \| Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	58	51
2020	23	35
2019	17	22
2018	9	10
2017	4	4
Prior	2	2
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	113	124
Special Mention \| Commercial and industrial \| Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	4	79
2020	17	152
2019	9	183
2018	12	98
2017	1	4
Prior	3	43
Revolving loans amortized cost basis	128	110
Revolving loans converted to term loans amortized cost basis	1	1
Total loans	175	670
Special Mention \| Leasing \| Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	0	1
2020	1	0
2019	4	2
2018	1	1
2017	1	0
Prior	0	6
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	7	10
Special Mention \| Owner-occupied \| Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	10	72
2020	13	65
2019	19	60
2018	32	60
2017	18	51
Prior	50	41
Revolving loans amortized cost basis	3	9
Revolving loans converted to term loans amortized cost basis	3	3
Total loans	148	361
Special Mention \| Municipal \| Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior	25	8
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	25	8
Special Mention \| Construction and land development \| Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	0	24
2020	0	43
2019	1	11
2018	0	0
2017	0	0
Prior	0	0
Revolving loans amortized cost basis	0	5
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	1	83
Special Mention \| Term \| Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	22	110
2020	39	89
2019	10	177
2018	17	42
2017	8	23
Prior	25	85
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	4	5
Total loans	125	531
Special Mention \| Home equity credit line \| Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior	0	0
Revolving loans amortized cost basis	1	2
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	1	2
Special Mention \| 1-4 family residential \| Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior	0	2
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	0	2
Special Mention \| Construction and other consumer real estate \| Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior	0	0
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	0	0
Special Mention \| Bankcard and other revolving plans \| Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior	0	0
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	0	0
Special Mention \| Other \| Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior	0	0
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	0	0
Accruing Substandard \| Commercial and industrial \| Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	28	123
2020	22	157
2019	99	129
2018	53	44
2017	31	26
Prior	65	17
Revolving loans amortized cost basis	162	141
Revolving loans converted to term loans amortized cost basis	3	6
Total loans	463	643
Accruing Substandard \| Leasing \| Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	0	2
2020	0	1
2019	0	1
2018	0	1
2017	0	0
Prior	5	0
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	5	5
Accruing Substandard \| Owner-occupied \| Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	14	28
2020	24	64
2019	41	61
2018	47	37
2017	24	35
Prior	79	98
Revolving loans amortized cost basis	13	6
Revolving loans converted to term loans amortized cost basis	0	1
Total loans	242	330
Accruing Substandard \| Municipal \| Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	0	0
2020	9	0
2019	0	0
2018	0	0
2017	0	0
Prior	5	9
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	14	9
Accruing Substandard \| Construction and land development \| Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	0	0
2020	3	30
2019	28	0
2018	0	0
2017	0	0
Prior	0	0
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	31	30
Accruing Substandard \| Term \| Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	9	41
2020	9	34
2019	44	96
2018	77	30
2017	14	18
Prior	64	34
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	2	0
Total loans	219	253
Accruing Substandard \| Home equity credit line \| Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0

Loans, Leases, and Allowance for Credit Losses (Summary of Outstanding Loan Balances (Accruing And Nonaccruing) Categorized By Credit Quality Indicators) (Details) - USD ($)
$ in Millions