Loans, Leases, and Allowance for Credit Losses (Summary of Outstanding Loan Balances (Accruing and Nonaccruing) Categorized by Credit Quality Indicators - Current Year) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Total loans
2024	$ 3,520		$ 3,520		$ 8,155
2023	7,785		7,785		12,553
2022	12,057		12,057		8,774
2021	7,910		7,910		4,982
2020	4,420		4,420		3,222
Prior	8,714		8,714		6,610
Revolving loans amortized cost basis	13,357		13,357		12,896
Revolving loans converted to term loans amortized cost basis	652		652		587
Total loans	58,415		58,415		57,779
Gross charge-offs
2024	0				1
2023	8				12
2022	5				6
2021	1				0
2020	0				1
Prior	3				4
Revolving loans amortized cost basis	4				36
Revolving loans converted to term loans amortized cost basis	0				2
Total	21	$ 22	35	$ 29	62
Commercial
Total loans
2024	1,798		1,798		4,492
2023	4,298		4,298		5,770
2022	5,122		5,122		4,436
2021	3,978		3,978		2,336
2020	2,135		2,135		1,729
Prior	4,289		4,289		3,201
Revolving loans amortized cost basis	8,628		8,628		8,410
Revolving loans converted to term loans amortized cost basis	263		263		214
Total loans	30,511		30,511		30,588
Gross charge-offs
2024	0				1
2023	1				10
2022	1				6
2021	1				0
2020	0				0
Prior	3				2
Revolving loans amortized cost basis	2				24
Revolving loans converted to term loans amortized cost basis	0				2
Total	8	20	18	23	45
Commercial real estate
Total loans
2024	1,209		1,209		2,571
2023	2,341		2,341		3,477
2022	3,513		3,513		2,294
2021	1,939		1,939		1,634
2020	1,314		1,314		884
Prior	2,049		2,049		1,482
Revolving loans amortized cost basis	900		900		757
Revolving loans converted to term loans amortized cost basis	284		284		272
Total loans	13,549		13,549		13,371
Gross charge-offs
2024	0				0
2023	7				2
2022	4				0
2021	0				0
2020	0				1
Prior	0				0
Revolving loans amortized cost basis	0				0
Revolving loans converted to term loans amortized cost basis	0				0
Total	11	0	11	0	3
Consumer
Total loans
2024	513		513		1,092
2023	1,146		1,146		3,306
2022	3,422		3,422		2,044
2021	1,993		1,993		1,012
2020	971		971		609
Prior	2,376		2,376		1,927
Revolving loans amortized cost basis	3,829		3,829		3,729
Revolving loans converted to term loans amortized cost basis	105		105		101
Total loans	14,355		14,355		13,820
Gross charge-offs
2024	0				0
2023	0				0
2022	0				0
2021	0				0
2020	0				0
Prior	0				2
Revolving loans amortized cost basis	2				12
Revolving loans converted to term loans amortized cost basis	0				0
Total	2	$ 2	6	$ 6	14
Commercial and industrial | Commercial
Total loans
2024	971		971		2,678
2023	2,498		2,498		2,572
2022	2,111		2,111		1,246
2021	1,066		1,066		645
2020	532		532		544
Prior	891		891		644
Revolving loans amortized cost basis	8,393		8,393		8,196
Revolving loans converted to term loans amortized cost basis	160		160		159
Total loans	16,622		16,622		16,684
Gross charge-offs
2024	0				1
2023	1				10
2022	1				6
2021	1				0
2020	0				0
Prior	3				2
Revolving loans amortized cost basis	2				24
Revolving loans converted to term loans amortized cost basis	0				2
Total	8				45
Leasing | Commercial
Total loans
2024	64		64		106
2023	92		92		136
2022	120		120		48
2021	39		39		30
2020	24		24		45
Prior	51		51		18
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	390		390		383
Gross charge-offs
2024	0				0
2023	0				0
2022	0				0
2021	0				0
2020	0				0
Prior	0				0
Revolving loans amortized cost basis	0				0
Revolving loans converted to term loans amortized cost basis	0				0
Total	0				0
Owner-occupied | Commercial
Total loans
2024	553		553		1,092
2023	1,143		1,143		1,982
2022	1,843		1,843		2,067
2021	1,908		1,908		1,035
2020	987		987		757
Prior	2,513		2,513		2,020
Revolving loans amortized cost basis	234		234		214
Revolving loans converted to term loans amortized cost basis	55		55		52
Total loans	9,236		9,236		9,219
Gross charge-offs
2024	0				0
2023	0				0
2022	0				0
2021	0				0
2020	0				0
Prior	0				0
Revolving loans amortized cost basis	0				0
Revolving loans converted to term loans amortized cost basis	0				0
Total	0				0
Municipal | Commercial
Total loans
2024	210		210		616
2023	565		565		1,080
2022	1,048		1,048		1,075
2021	965		965		626
2020	592		592		383
Prior	834		834		519
Revolving loans amortized cost basis	1		1		0
Revolving loans converted to term loans amortized cost basis	48		48		3
Total loans	4,263		4,263		4,302
Gross charge-offs
2024	0				0
2023	0				0
2022	0				0
2021	0				0
2020	0				0
Prior	0				0
Revolving loans amortized cost basis	0				0
Revolving loans converted to term loans amortized cost basis	0				0
Total	0				0
Construction and land development | Commercial real estate
Total loans
2024	248		248		576
2023	679		679		940
2022	882		882		384
2021	221		221		91
2020	36		36		28
Prior	10		10		4
Revolving loans amortized cost basis	592		592		519
Revolving loans converted to term loans amortized cost basis	57		57		127
Total loans	2,725		2,725		2,669
Gross charge-offs
2024	0				0
2023	0				0
2022	0				0
2021	0				0
2020	0				1
Prior	0				0
Revolving loans amortized cost basis	0				0
Revolving loans converted to term loans amortized cost basis	0				0
Total	0				1
Term | Commercial real estate
Total loans
2024	961		961		1,995
2023	1,662		1,662		2,537
2022	2,631		2,631		1,910
2021	1,718		1,718		1,543
2020	1,278		1,278		856
Prior	2,039		2,039		1,478
Revolving loans amortized cost basis	308		308		238
Revolving loans converted to term loans amortized cost basis	227		227		145
Total loans	10,824		10,824		10,702
Gross charge-offs
2024	0				0
2023	7				2
2022	4				0
2021	0				0
2020	0				0
Prior	0				0
Revolving loans amortized cost basis	0				0
Revolving loans converted to term loans amortized cost basis	0				0
Total	11				2
Home equity credit line | Consumer
Total loans
2024	0		0		0
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	3,365		3,365		3,256
Revolving loans converted to term loans amortized cost basis	103		103		100
Total loans	3,468		3,468		3,356
Gross charge-offs
2024	0				0
2023	0				0
2022	0				0
2021	0				0
2020	0				0
Prior	0				0
Revolving loans amortized cost basis	0				3
Revolving loans converted to term loans amortized cost basis	0				0
Total	0				3
1-4 family residential | Consumer
Total loans
2024	439		439		814
2023	821		821		2,267
2022	2,666		2,666		1,826
2021	1,904		1,904		991
2020	958		958		598
Prior	2,365		2,365		1,919
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	9,153		9,153		8,415
Gross charge-offs
2024	0				0
2023	0				0
2022	0				0
2021	0				0
2020	0				0
Prior	0				2
Revolving loans amortized cost basis	0				0
Revolving loans converted to term loans amortized cost basis	0				0
Total	0				2
Construction and other consumer real estate | Consumer
Total loans
2024	38		38		212
2023	280		280		1,002
2022	727		727		200
2021	77		77		15
2020	9		9		7
Prior	8		8		6
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	1,139		1,139		1,442
Gross charge-offs
2024	0				0
2023	0				0
2022	0				0
2021	0				0
2020	0				0
Prior	0				0
Revolving loans amortized cost basis	0				0
Revolving loans converted to term loans amortized cost basis	0				0
Total	0				0
Bankcard and other revolving plans | Consumer
Total loans
2024	0		0		0
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	464		464		473
Revolving loans converted to term loans amortized cost basis	2		2		1
Total loans	466		466		474
Gross charge-offs
2024	0				0
2023	0				0
2022	0				0
2021	0				0
2020	0				0
Prior	0				0
Revolving loans amortized cost basis	2				9
Revolving loans converted to term loans amortized cost basis	0				0
Total	2				9
Other | Consumer
Total loans
2024	36		36		66
2023	45		45		37
2022	29		29		18
2021	12		12		6
2020	4		4		4
Prior	3		3		2
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	129		129		133
Gross charge-offs
2024	0				0
2023	0				0
2022	0				0
2021	0				0
2020	0				0
Prior	0				0
Revolving loans amortized cost basis	0				0
Revolving loans converted to term loans amortized cost basis	0				0
Total	0				0
Pass | Commercial and industrial | Commercial
Total loans
2024	943		943		2,654
2023	2,411		2,411		2,420
2022	1,938		1,938		1,204
2021	1,014		1,014		639
2020	524		524		494
Prior	854		854		598
Revolving loans amortized cost basis	8,172		8,172		7,973
Revolving loans converted to term loans amortized cost basis	150		150		151
Total loans	16,006		16,006		16,133
Pass | Leasing | Commercial
Total loans
2024	63		63		104
2023	89		89		125
2022	110		110		47
2021	37		37		29
2020	23		23		45
Prior	51		51		18
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	373		373		368
Pass | Owner-occupied | Commercial
Total loans
2024	543		543		1,080
2023	1,115		1,115		1,945
2022	1,770		1,770		2,020
2021	1,852		1,852		1,002
2020	956		956		721
Prior	2,350		2,350		1,907
Revolving loans amortized cost basis	213		213		212
Revolving loans converted to term loans amortized cost basis	50		50		52
Total loans	8,849		8,849		8,939
Pass | Municipal | Commercial
Total loans
2024	207		207		601
2023	552		552		1,080
2022	1,048		1,048		1,069
2021	959		959		623
2020	592		592		382
Prior	831		831		512
Revolving loans amortized cost basis	1		1		0
Revolving loans converted to term loans amortized cost basis	48		48		3
Total loans	4,238		4,238		4,270
Pass | Construction and land development | Commercial real estate
Total loans
2024	247		247		553
2023	660		660		938
2022	838		838		355
2021	142		142		56
2020	36		36		7
Prior	10		10		4
Revolving loans amortized cost basis	590		590		518
Revolving loans converted to term loans amortized cost basis	57		57		127
Total loans	2,580		2,580		2,558
Pass | Term | Commercial real estate
Total loans
2024	783		783		1,861
2023	1,576		1,576		2,385
2022	2,276		2,276		1,833
2021	1,601		1,601		1,449
2020	1,180		1,180		804
Prior	1,973		1,973		1,438
Revolving loans amortized cost basis	308		308		238
Revolving loans converted to term loans amortized cost basis	183		183		110
Total loans	9,880		9,880		10,118
Pass | Home equity credit line | Consumer
Total loans
2024	0		0		0
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	3,336		3,336		3,237
Revolving loans converted to term loans amortized cost basis	96		96		97
Total loans	3,432		3,432		3,334
Pass | 1-4 family residential | Consumer
Total loans
2024	439		439		814
2023	820		820		2,264
2022	2,659		2,659		1,823
2021	1,898		1,898		988
2020	956		956		594
Prior	2,335		2,335		1,891
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	9,107		9,107		8,374
Pass | Construction and other consumer real estate | Consumer
Total loans
2024	38		38		212
2023	280		280		1,002
2022	727		727		200
2021	77		77		15
2020	9		9		7
Prior	8		8		6
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	1,139		1,139		1,442
Pass | Bankcard and other revolving plans | Consumer
Total loans
2024	0		0		0
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	463		463		471
Revolving loans converted to term loans amortized cost basis	1		1		1
Total loans	464		464		472
Pass | Other | Consumer
Total loans
2024	36		36		66
2023	44		44		37
2022	29		29		18
2021	12		12		6
2020	4		4		4
Prior	3		3		2
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	128		128		133
Special Mention | Commercial and industrial | Commercial
Total loans
2024	1		1		8
2023	14		14		98
2022	54		54		34
2021	19		19		2
2020	3		3		20
Prior	3		3		37
Revolving loans amortized cost basis	34		34		103
Revolving loans converted to term loans amortized cost basis	2		2		0
Total loans	130		130		302
Special Mention | Leasing | Commercial
Total loans
2024	0		0		2
2023	2		2		9
2022	8		8		1
2021	1		1		1
2020	1		1		0
Prior	0		0		0
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	12		12		13
Special Mention | Owner-occupied | Commercial
Total loans
2024	5		5		2
2023	3		3		5
2022	16		16		17
2021	15		15		5
2020	1		1		17
Prior	24		24		15
Revolving loans amortized cost basis	11		11		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	75		75		61
Special Mention | Municipal | Commercial
Total loans
2024	0		0		7
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
Prior	0		0		6
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	0		0		13
Special Mention | Construction and land development | Commercial real estate
Total loans
2024	0		0		0
2023	0		0		0
2022	44		44		29
2021	74		74		30
2020	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	118		118		59
Special Mention | Term | Commercial real estate
Total loans
2024	134		134		55
2023	19		19		108
2022	253		253		65
2021	98		98		78
2020	81		81		44
Prior	26		26		6
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	611		611		356
Special Mention | Home equity credit line | Consumer
Total loans
2024	0		0		0
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	0		0		0
Special Mention | 1-4 family residential | Consumer
Total loans
2024	0		0		0
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	0		0		0
Special Mention | Construction and other consumer real estate | Consumer
Total loans
2024	0		0		0
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	0		0		0
Special Mention | Bankcard and other revolving plans | Consumer
Total loans
2024	0		0		0
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	0		0		0
Special Mention | Other | Consumer
Total loans
2024	0		0		0
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	0		0		0
Accruing Substandard | Commercial and industrial | Commercial
Total loans
2024	27		27		11
2023	57		57		18
2022	85		85		7
2021	32		32		2
2020	3		3		19
Prior	23		23		8
Revolving loans amortized cost basis	145		145		99
Revolving loans converted to term loans amortized cost basis	3		3		3
Total loans	375		375		167
Accruing Substandard | Leasing | Commercial
Total loans
2024	1		1		0
2023	1		1		0
2022	0		0		0
2021	1		1		0
2020	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	3		3		0
Accruing Substandard | Owner-occupied | Commercial
Total loans
2024	1		1		10
2023	25		25		31
2022	55		55		29
2021	40		40		21
2020	30		30		16
Prior	124		124		90
Revolving loans amortized cost basis	4		4		2
Revolving loans converted to term loans amortized cost basis	5		5		0
Total loans	284		284		199
Accruing Substandard | Municipal | Commercial
Total loans
2024	0		0		8
2023	13		13		0
2022	0		0		6
2021	6		6		3
2020	0		0		1
Prior	0		0		1
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	19		19		19
Accruing Substandard | Construction and land development | Commercial real estate
Total loans
2024	1		1		23
2023	19		19		2
2022	0		0		0
2021	5		5		5
2020	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	25		25		30
Accruing Substandard | Term | Commercial real estate
Total loans
2024	44		44		79
2023	65		65		18
2022	80		80		12
2021	19		19		16
2020	17		17		5
Prior	29		29		24
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	44		44		35
Total loans	298		298		189
Accruing Substandard | Home equity credit line | Consumer
Total loans
2024	0		0		0
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	6		6		4
Revolving loans converted to term loans amortized cost basis	1		1		1
Total loans	7		7		5
Accruing Substandard | 1-4 family residential | Consumer
Total loans
2024	0		0		0
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
Prior	0		0		1
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	0		0		1
Accruing Substandard | Construction and other consumer real estate | Consumer
Total loans
2024	0		0		0
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	0		0		0
Accruing Substandard | Bankcard and other revolving plans | Consumer
Total loans
2024	0		0		0
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	1		1		2
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	1		1		2
Accruing Substandard | Other | Consumer
Total loans
2024	0		0		0
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	0		0		0
Nonaccrual | Commercial and industrial | Commercial
Total loans
2024	0		0		5
2023	16		16		36
2022	34		34		1
2021	1		1		2
2020	2		2		11
Prior	11		11		1
Revolving loans amortized cost basis	42		42		21
Revolving loans converted to term loans amortized cost basis	5		5		5
Total loans	111		111		82
Nonaccrual | Leasing | Commercial
Total loans
2024	0		0		0
2023	0		0		2
2022	2		2		0
2021	0		0		0
2020	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	2		2		2
Nonaccrual | Owner-occupied | Commercial
Total loans
2024	4		4		0
2023	0		0		1
2022	2		2		1
2021	1		1		7
2020	0		0		3
Prior	15		15		8
Revolving loans amortized cost basis	6		6		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	28		28		20
Nonaccrual | Municipal | Commercial
Total loans
2024	3		3		0
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
Prior	3		3		0
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	6		6		0
Nonaccrual | Construction and land development | Commercial real estate
Total loans
2024	0		0		0
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		21
Prior	0		0		0
Revolving loans amortized cost basis	2		2		1
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	2		2		22
Nonaccrual | Term | Commercial real estate
Total loans
2024	0		0		0
2023	2		2		26
2022	22		22		0
2021	0		0		0
2020	0		0		3
Prior	11		11		10
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	35		35		39
Nonaccrual | Home equity credit line | Consumer
Total loans
2024	0		0		0
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	23		23		15
Revolving loans converted to term loans amortized cost basis	6		6		2
Total loans	29		29		17
Nonaccrual | 1-4 family residential | Consumer
Total loans
2024	0		0		0
2023	1		1		3
2022	7		7		3
2021	6		6		3
2020	2		2		4
Prior	30		30		27
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	46		46		40
Nonaccrual | Construction and other consumer real estate | Consumer
Total loans
2024	0		0		0
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	0		0		0
Nonaccrual | Bankcard and other revolving plans | Consumer
Total loans
2024	0		0		0
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	1		1		0
Total loans	1		1		0
Nonaccrual | Other | Consumer
Total loans
2024	0		0		0
2023	1		1		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	$ 1		$ 1		$ 0