Loans, Leases, and Allowance for Credit Losses (Summary of Outstanding Loan Balances (Accruing and Nonaccruing) Categorized by Credit Quality Indicators - Prior Year) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Total loans
2022/2021	$ 8,155	$ 13,059
2021/2020	12,553	10,344
2020/2019	8,774	6,360
2019/2018	4,982	4,239
2018/2017	3,222	2,347
Prior	6,610	5,667
Revolving loans amortized cost basis	12,896	13,064
Revolving loans converted to term loans amortized cost basis	587	573
Total loans	57,779	55,653
Gross charge-offs
2022	1
2021	12
2020	6
2019	0
2018	1
Prior	4
Revolving loans amortized cost basis	36
Revolving loans converted to term loans amortized cost basis	2
Total	62	82
Commercial
Total loans
2022/2021	4,492	6,987
2021/2020	5,770	5,522
2020/2019	4,436	3,072
2019/2018	2,336	2,430
2018/2017	1,729	1,228
Prior	3,201	2,568
Revolving loans amortized cost basis	8,410	8,426
Revolving loans converted to term loans amortized cost basis	214	262
Total loans	30,588	30,495
Gross charge-offs
2022	1
2021	10
2020	6
2019	0
2018	0
Prior	2
Revolving loans amortized cost basis	24
Revolving loans converted to term loans amortized cost basis	2
Total	45	72
Commercial real estate
Total loans
2022/2021	2,571	3,508
2021/2020	3,477	2,802
2020/2019	2,294	2,186
2019/2018	1,634	1,140
2018/2017	884	726
Prior	1,482	1,276
Revolving loans amortized cost basis	757	893
Revolving loans converted to term loans amortized cost basis	272	208
Total loans	13,371	12,739
Gross charge-offs
2022	0
2021	2
2020	0
2019	0
2018	1
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total	3	0
Consumer
Total loans
2022/2021	1,092	2,564
2021/2020	3,306	2,020
2020/2019	2,044	1,102
2019/2018	1,012	669
2018/2017	609	393
Prior	1,927	1,823
Revolving loans amortized cost basis	3,729	3,745
Revolving loans converted to term loans amortized cost basis	101	103
Total loans	13,820	12,419
Gross charge-offs
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	2
Revolving loans amortized cost basis	12
Revolving loans converted to term loans amortized cost basis	0
Total	14	10
Commercial and industrial | Commercial
Total loans
2022/2021	2,678	3,390
2021/2020	2,572	1,891
2020/2019	1,246	1,011
2019/2018	645	1,017
2018/2017	544	325
Prior	644	335
Revolving loans amortized cost basis	8,196	8,220
Revolving loans converted to term loans amortized cost basis	159	188
Total loans	16,684	16,377
Gross charge-offs
2022	1
2021	10
2020	6
2019	0
2018	0
Prior	2
Revolving loans amortized cost basis	24
Revolving loans converted to term loans amortized cost basis	2
Total	45
Leasing | Commercial
Total loans
2022/2021	106	160
2021/2020	136	71
2020/2019	48	47
2019/2018	30	66
2018/2017	45	18
Prior	18	24
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	383	386
Gross charge-offs
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total	0
Owner-occupied | Commercial
Total loans
2022/2021	1,092	2,175
2021/2020	1,982	2,334
2020/2019	2,067	1,198
2019/2018	1,035	906
2018/2017	757	717
Prior	2,020	1,769
Revolving loans amortized cost basis	214	198
Revolving loans converted to term loans amortized cost basis	52	74
Total loans	9,219	9,371
Gross charge-offs
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total	0
Municipal | Commercial
Total loans
2022/2021	616	1,262
2021/2020	1,080	1,226
2020/2019	1,075	816
2019/2018	626	441
2018/2017	383	168
Prior	519	440
Revolving loans amortized cost basis	0	8
Revolving loans converted to term loans amortized cost basis	3	0
Total loans	4,302	4,361
Gross charge-offs
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total	0
Construction and land development | Commercial real estate
Total loans
2022/2021	576	566
2021/2020	940	672
2020/2019	384	455
2019/2018	91	103
2018/2017	28	2
Prior	4	2
Revolving loans amortized cost basis	519	617
Revolving loans converted to term loans amortized cost basis	127	96
Total loans	2,669	2,513
Gross charge-offs
2022	0
2021	0
2020	0
2019	0
2018	1
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total	1
Term | Commercial real estate
Total loans
2022/2021	1,995	2,942
2021/2020	2,537	2,130
2020/2019	1,910	1,731
2019/2018	1,543	1,037
2018/2017	856	724
Prior	1,478	1,274
Revolving loans amortized cost basis	238	276
Revolving loans converted to term loans amortized cost basis	145	112
Total loans	10,702	10,226
Gross charge-offs
2022	0
2021	2
2020	0
2019	0
2018	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total	2
Home equity credit line | Consumer
Total loans
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
2018/2017	0	0
Prior	0	0
Revolving loans amortized cost basis	3,256	3,276
Revolving loans converted to term loans amortized cost basis	100	101
Total loans	3,356	3,377
Gross charge-offs
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Revolving loans amortized cost basis	3
Revolving loans converted to term loans amortized cost basis	0
Total	3
1-4 family residential | Consumer
Total loans
2022/2021	814	1,913
2021/2020	2,267	1,505
2020/2019	1,826	1,026
2019/2018	991	642
2018/2017	598	384
Prior	1,919	1,816
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	8,415	7,286
Gross charge-offs
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	2
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total	2
Construction and other consumer real estate | Consumer
Total loans
2022/2021	212	583
2021/2020	1,002	485
2020/2019	200	64
2019/2018	15	19
2018/2017	7	5
Prior	6	5
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	1,442	1,161
Gross charge-offs
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total	0
Bankcard and other revolving plans | Consumer
Total loans
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
2018/2017	0	0
Prior	0	0
Revolving loans amortized cost basis	473	469
Revolving loans converted to term loans amortized cost basis	1	2
Total loans	474	471
Gross charge-offs
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Revolving loans amortized cost basis	9
Revolving loans converted to term loans amortized cost basis	0
Total	9
Other | Consumer
Total loans
2022/2021	66	68
2021/2020	37	30
2020/2019	18	12
2019/2018	6	8
2018/2017	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	133	124
Gross charge-offs
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total	0
Pass | Commercial and industrial | Commercial
Total loans
2022/2021	2,654	3,363
2021/2020	2,420	1,874
2020/2019	1,204	979
2019/2018	639	876
2018/2017	494	293
Prior	598	264
Revolving loans amortized cost basis	7,973	8,054
Revolving loans converted to term loans amortized cost basis	151	182
Total loans	16,133	15,885
Pass | Leasing | Commercial
Total loans
2022/2021	104	160
2021/2020	125	71
2020/2019	47	47
2019/2018	29	66
2018/2017	45	18
Prior	18	19
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	368	381
Pass | Owner-occupied | Commercial
Total loans
2022/2021	1,080	2,157
2021/2020	1,945	2,285
2020/2019	2,020	1,143
2019/2018	1,002	874
2018/2017	721	654
Prior	1,907	1,679
Revolving loans amortized cost basis	212	187
Revolving loans converted to term loans amortized cost basis	52	74
Total loans	8,939	9,053
Pass | Municipal | Commercial
Total loans
2022/2021	601	1,230
2021/2020	1,080	1,220
2020/2019	1,069	816
2019/2018	623	441
2018/2017	382	168
Prior	512	437
Revolving loans amortized cost basis	0	8
Revolving loans converted to term loans amortized cost basis	3	0
Total loans	4,270	4,320
Pass | Construction and land development | Commercial real estate
Total loans
2022/2021	553	548
2021/2020	938	671
2020/2019	355	455
2019/2018	56	81
2018/2017	7	2
Prior	4	2
Revolving loans amortized cost basis	518	617
Revolving loans converted to term loans amortized cost basis	127	96
Total loans	2,558	2,472
Pass | Term | Commercial real estate
Total loans
2022/2021	1,861	2,861
2021/2020	2,385	2,107
2020/2019	1,833	1,686
2019/2018	1,449	1,012
2018/2017	804	666
Prior	1,438	1,229
Revolving loans amortized cost basis	238	276
Revolving loans converted to term loans amortized cost basis	110	112
Total loans	10,118	9,949
Pass | Home equity credit line | Consumer
Total loans
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
2018/2017	0	0
Prior	0	0
Revolving loans amortized cost basis	3,237	3,265
Revolving loans converted to term loans amortized cost basis	97	98
Total loans	3,334	3,363
Pass | 1-4 family residential | Consumer
Total loans
2022/2021	814	1,913
2021/2020	2,264	1,503
2020/2019	1,823	1,024
2019/2018	988	638
2018/2017	594	381
Prior	1,891	1,788
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	8,374	7,247
Pass | Construction and other consumer real estate | Consumer
Total loans
2022/2021	212	583
2021/2020	1,002	485
2020/2019	200	64
2019/2018	15	19
2018/2017	7	5
Prior	6	5
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	1,442	1,161
Pass | Bankcard and other revolving plans | Consumer
Total loans
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
2018/2017	0	0
Prior	0	0
Revolving loans amortized cost basis	471	468
Revolving loans converted to term loans amortized cost basis	1	2
Total loans	472	470
Pass | Other | Consumer
Total loans
2022/2021	66	68
2021/2020	37	30
2020/2019	18	12
2019/2018	6	8
2018/2017	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	133	124
Special Mention | Commercial and industrial | Commercial
Total loans
2022/2021	8	1
2021/2020	98	2
2020/2019	34	10
2019/2018	2	52
2018/2017	20	1
Prior	37	2
Revolving loans amortized cost basis	103	50
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	302	118
Special Mention | Leasing | Commercial
Total loans
2022/2021	2	0
2021/2020	9	0
2020/2019	1	0
2019/2018	1	0
2018/2017	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	13	0
Special Mention | Owner-occupied | Commercial
Total loans
2022/2021	2	1
2021/2020	5	15
2020/2019	17	5
2019/2018	5	8
2018/2017	17	3
Prior	15	16
Revolving loans amortized cost basis	0	1
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	61	49
Special Mention | Municipal | Commercial
Total loans
2022/2021	7	32
2021/2020	0	6
2020/2019	0	0
2019/2018	0	0
2018/2017	0	0
Prior	6	0
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	13	38
Special Mention | Construction and land development | Commercial real estate
Total loans
2022/2021	0	1
2021/2020	0	1
2020/2019	29	0
2019/2018	30	0
2018/2017	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	59	2
Special Mention | Term | Commercial real estate
Total loans
2022/2021	55	39
2021/2020	108	21
2020/2019	65	11
2019/2018	78	0
2018/2017	44	4
Prior	6	1
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	356	76
Special Mention | Home equity credit line | Consumer
Total loans
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
2018/2017	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 | 1-4 family residential | Consumer
Total loans
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
2018/2017	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 | Construction and other consumer real estate | Consumer
Total loans
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
2018/2017	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
Total loans
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
2018/2017	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
Total loans
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
2018/2017	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
Total loans
2022/2021	11	26
2021/2020	18	7
2020/2019	7	17
2019/2018	2	78
2018/2017	19	30
Prior	8	67
Revolving loans amortized cost basis	99	84
Revolving loans converted to term loans amortized cost basis	3	2
Total loans	167	311
Accruing Substandard | Leasing | Commercial
Total loans
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
2018/2017	0	0
Prior	0	5
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	0	5
Accruing Substandard | Owner-occupied | Commercial
Total loans
2022/2021	10	16
2021/2020	31	33
2020/2019	29	48
2019/2018	21	20
2018/2017	16	55
Prior	90	64
Revolving loans amortized cost basis	2	9
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	199	245
Accruing Substandard | Municipal | Commercial
Total loans
2022/2021	8	0
2021/2020	0	0
2020/2019	6	0
2019/2018	3	0
2018/2017	1	0
Prior	1	3
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	19	3
Accruing Substandard | Construction and land development | Commercial real estate
Total loans
2022/2021	23	17
2021/2020	2	0
2020/2019	0	0
2019/2018	5	22
2018/2017	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	30	39
Accruing Substandard | Term | Commercial real estate
Total loans
2022/2021	79	42
2021/2020	18	2
2020/2019	12	34
2019/2018	16	21
2018/2017	5	53
Prior	24	35
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	35	0
Total loans	189	187
Accruing Substandard | Home equity credit line | Consumer
Total loans
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
2018/2017	0	0
Prior	0	0
Revolving loans amortized cost basis	4	3
Revolving loans converted to term loans amortized cost basis	1	0
Total loans	5	3
Accruing Substandard | 1-4 family residential | Consumer
Total loans
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
2018/2017	0	0
Prior	1	2
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	1	2
Accruing Substandard | Construction and other consumer real estate | Consumer
Total loans
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
2018/2017	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 | Bankcard and other revolving plans | Consumer
Total loans
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
2018/2017	0	0
Prior	0	0
Revolving loans amortized cost basis	2	1
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	2	1
Accruing Substandard | Other | Consumer
Total loans
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
2018/2017	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
Nonaccrual | Commercial and industrial | Commercial
Total loans
2022/2021	5	0
2021/2020	36	8
2020/2019	1	5
2019/2018	2	11
2018/2017	11	1
Prior	1	2
Revolving loans amortized cost basis	21	32
Revolving loans converted to term loans amortized cost basis	5	4
Total loans	82	63
Nonaccrual | Leasing | Commercial
Total loans
2022/2021	0	0
2021/2020	2	0
2020/2019	0	0
2019/2018	0	0
2018/2017	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	2	0
Nonaccrual | Owner-occupied | Commercial
Total loans
2022/2021	0	1
2021/2020	1	1
2020/2019	1	2
2019/2018	7	4
2018/2017	3	5
Prior	8	10
Revolving loans amortized cost basis	0	1
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	20	24
Nonaccrual | Municipal | Commercial
Total loans
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
2018/2017	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
Nonaccrual | Construction and land development | Commercial real estate
Total loans
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
2018/2017	21	0
Prior	0	0
Revolving loans amortized cost basis	1	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	22	0
Nonaccrual | Term | Commercial real estate
Total loans
2022/2021	0	0
2021/2020	26	0
2020/2019	0	0
2019/2018	0	4
2018/2017	3	1
Prior	10	9
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	39	14
Nonaccrual | Home equity credit line | Consumer
Total loans
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
2018/2017	0	0
Prior	0	0
Revolving loans amortized cost basis	15	8
Revolving loans converted to term loans amortized cost basis	2	3
Total loans	17	11
Nonaccrual | 1-4 family residential | Consumer
Total loans
2022/2021	0	0
2021/2020	3	2
2020/2019	3	2
2019/2018	3	4
2018/2017	4	3
Prior	27	26
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans amortized cost basis	0	0
Total loans	40	37
Nonaccrual | Construction and other consumer real estate | Consumer
Total loans
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
2018/2017	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
Nonaccrual | Bankcard and other revolving plans | Consumer
Total loans
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
2018/2017	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
Nonaccrual | Other | Consumer
Total loans
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
2018/2017	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