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	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Total loans
2023	$ 5,741		$ 5,741		$ 8,155
2022	7,386		7,386		12,553
2021	11,730		11,730		8,774
2020	7,631		7,631		4,982
2019	4,158		4,158		3,222
Prior	8,245		8,245		6,610
Revolving loans amortized cost basis	13,396		13,396		12,896
Revolving loans converted to term loans amortized cost basis	597		597		587
Total loans	58,884		58,884		57,779
Gross charge-offs by year of loan origination
2023	0	$ 1	0	$ 1
2022	1	6	10	12
2021	5	0	13	5
2020	0	0	2	0
2019	0	1	0	1
Prior	1	0	6	3
Revolving loans gross charge-offs	7	12	17	25
Revolving loans converted to term loans gross charge-offs	1	0	2	2
Total	15	20	50	49
Commercial
Total loans
2023	3,221		3,221		4,492
2022	4,059		4,059		5,770
2021	4,833		4,833		4,436
2020	3,841		3,841		2,336
2019	2,028		2,028		1,729
Prior	4,025		4,025		3,201
Revolving loans amortized cost basis	8,559		8,559		8,410
Revolving loans converted to term loans amortized cost basis	219		219		214
Total loans	30,785		30,785		30,588
Gross charge-offs by year of loan origination
2023	0		0
2022	1		3
2021	5		9
2020	0		2
2019	0		0
Prior	1		4
Revolving loans gross charge-offs	4		10
Revolving loans converted to term loans gross charge-offs	1		2
Total	12	12	30	35
Commercial real estate
Total loans
2023	1,682		1,682		2,571
2022	2,191		2,191		3,477
2021	3,471		3,471		2,294
2020	1,832		1,832		1,634
2019	1,173		1,173		884
Prior	1,923		1,923		1,482
Revolving loans amortized cost basis	937		937		757
Revolving loans converted to term loans amortized cost basis	274		274		272
Total loans	13,483		13,483		13,371
Gross charge-offs by year of loan origination
2023		0		0
2022		2		2
2021		0		0
2020		0		0
2019		1		1
Prior		0		0
Revolving loans gross charge-offs		0		0
Revolving loans converted to term loans gross charge-offs		0		0
Total	0	3	11	3
Consumer
Total loans
2023	838		838		1,092
2022	1,136		1,136		3,306
2021	3,426		3,426		2,044
2020	1,958		1,958		1,012
2019	957		957		609
Prior	2,297		2,297		1,927
Revolving loans amortized cost basis	3,900		3,900		3,729
Revolving loans converted to term loans amortized cost basis	104		104		101
Total loans	14,616		14,616		13,820
Gross charge-offs by year of loan origination
2023	0	0	0	0
2022	0	0	0	0
2021	0	0	0	0
2020	0	0	0	0
2019	0	0	0	0
Prior	0	0	2	2
Revolving loans gross charge-offs	3	5	7	9
Revolving loans converted to term loans gross charge-offs	0	0	0	0
Total	3	5	9	11
Commercial and industrial | Commercial
Total loans
2023	1,757		1,757		2,678
2022	2,364		2,364		2,572
2021	1,964		1,964		1,246
2020	974		974		645
2019	479		479		544
Prior	798		798		644
Revolving loans amortized cost basis	8,276		8,276		8,196
Revolving loans converted to term loans amortized cost basis	145		145		159
Total loans	16,757		16,757		16,684
Gross charge-offs by year of loan origination
2023	0	1	0	1
2022	1	4	3	10
2021	4	0	8	5
2020	0	0	2	0
2019	0	0	0	0
Prior	1	0	4	1
Revolving loans gross charge-offs	4	7	10	16
Revolving loans converted to term loans gross charge-offs	1	0	2	2
Total	11	12	29	35
Leasing | Commercial
Total loans
2023	74		74		106
2022	88		88		136
2021	114		114		48
2020	35		35		30
2019	19		19		45
Prior	47		47		18
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	377		377		383
Owner-occupied | Commercial
Total loans
2023	944		944		1,092
2022	1,108		1,108		1,982
2021	1,806		1,806		2,067
2020	1,848		1,848		1,035
2019	952		952		757
Prior	2,388		2,388		2,020
Revolving loans amortized cost basis	279		279		214
Revolving loans converted to term loans amortized cost basis	56		56		52
Total loans	9,381		9,381		9,219
Gross charge-offs by year of loan origination
2023	0		0
2022	0		0
2021	1		1
2020	0		0
2019	0		0
Prior	0		0
Revolving loans gross charge-offs	0		0
Revolving loans converted to term loans gross charge-offs	0		0
Total	1		1
Municipal | Commercial
Total loans
2023	446		446		616
2022	499		499		1,080
2021	949		949		1,075
2020	984		984		626
2019	578		578		383
Prior	792		792		519
Revolving loans amortized cost basis	4		4		0
Revolving loans converted to term loans amortized cost basis	18		18		3
Total loans	4,270		4,270		4,302
Construction and land development | Commercial real estate
Total loans
2023	313		313		576
2022	751		751		940
2021	840		840		384
2020	189		189		91
2019	1		1		28
Prior	10		10		4
Revolving loans amortized cost basis	662		662		519
Revolving loans converted to term loans amortized cost basis	67		67		127
Total loans	2,833		2,833		2,669
Gross charge-offs by year of loan origination
2023		0		0
2022		0		0
2021		0		0
2020		0		0
2019		1		1
Prior		0		0
Revolving loans gross charge-offs		0		0
Revolving loans converted to term loans gross charge-offs		0		0
Total		1		1
Term | Commercial real estate
Total loans
2023	1,369		1,369		1,995
2022	1,440		1,440		2,537
2021	2,631		2,631		1,910
2020	1,643		1,643		1,543
2019	1,172		1,172		856
Prior	1,913		1,913		1,478
Revolving loans amortized cost basis	275		275		238
Revolving loans converted to term loans amortized cost basis	207		207		145
Total loans	10,650		10,650		10,702
Gross charge-offs by year of loan origination
2023		0	0	0
2022		2	7	2
2021		0	4	0
2020		0	0	0
2019		0	0	0
Prior		0	0	0
Revolving loans gross charge-offs		0	0	0
Revolving loans converted to term loans gross charge-offs		0	0	0
Total		2	11	2
Home equity credit line | Consumer
Total loans
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	3,440		3,440		3,256
Revolving loans converted to term loans amortized cost basis	103		103		100
Total loans	3,543		3,543		3,356
Gross charge-offs by year of loan origination
2023	0	0	0	0
2022	0	0	0	0
2021	0	0	0	0
2020	0	0	0	0
2019	0	0	0	0
Prior	0	0	0	0
Revolving loans gross charge-offs	1	3	1	3
Revolving loans converted to term loans gross charge-offs	0	0	0	0
Total	1	3	1	3
1-4 family residential | Consumer
Total loans
2023	697		697		814
2022	845		845		2,267
2021	2,818		2,818		1,826
2020	1,891		1,891		991
2019	946		946		598
Prior	2,292		2,292		1,919
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	9,489		9,489		8,415
Gross charge-offs by year of loan origination
2023			0	0
2022			0	0
2021			0	0
2020			0	0
2019			0	0
Prior			1	2
Revolving loans gross charge-offs			0	0
Revolving loans converted to term loans gross charge-offs			0	0
Total			1	2
Construction and other consumer real estate | Consumer
Total loans
2023	95		95		212
2022	251		251		1,002
2021	583		583		200
2020	57		57		15
2019	8		8		7
Prior	3		3		6
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	997		997		1,442
Bankcard and other revolving plans | Consumer
Total loans
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	460		460		473
Revolving loans converted to term loans amortized cost basis	1		1		1
Total loans	461		461		474
Gross charge-offs by year of loan origination
2023	0	0	0	0
2022	0	0	0	0
2021	0	0	0	0
2020	0	0	0	0
2019	0	0	0	0
Prior	0	0	0	0
Revolving loans gross charge-offs	2	2	6	6
Revolving loans converted to term loans gross charge-offs	0	0	0	0
Total	2	$ 2	6	$ 6
Other | Consumer
Total loans
2023	46		46		66
2022	40		40		37
2021	25		25		18
2020	10		10		6
2019	3		3		4
Prior	2		2		2
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	126		126		133
Gross charge-offs by year of loan origination
2023			0
2022			0
2021			0
2020			0
2019			0
Prior			1
Revolving loans gross charge-offs			0
Revolving loans converted to term loans gross charge-offs			0
Total			1
Pass | Commercial and industrial | Commercial
Total loans
2023	1,707		1,707		2,654
2022	2,281		2,281		2,420
2021	1,741		1,741		1,204
2020	918		918		639
2019	473		473		494
Prior	752		752		598
Revolving loans amortized cost basis	8,000		8,000		7,973
Revolving loans converted to term loans amortized cost basis	135		135		151
Total loans	16,007		16,007		16,133
Pass | Leasing | Commercial
Total loans
2023	73		73		104
2022	85		85		125
2021	104		104		47
2020	33		33		29
2019	18		18		45
Prior	47		47		18
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	360		360		368
Pass | Owner-occupied | Commercial
Total loans
2023	934		934		1,080
2022	1,080		1,080		1,945
2021	1,715		1,715		2,020
2020	1,789		1,789		1,002
2019	923		923		721
Prior	2,220		2,220		1,907
Revolving loans amortized cost basis	253		253		212
Revolving loans converted to term loans amortized cost basis	51		51		52
Total loans	8,965		8,965		8,939
Pass | Municipal | Commercial
Total loans
2023	443		443		601
2022	486		486		1,080
2021	949		949		1,069
2020	979		979		623
2019	578		578		382
Prior	789		789		512
Revolving loans amortized cost basis	4		4		0
Revolving loans converted to term loans amortized cost basis	18		18		3
Total loans	4,246		4,246		4,270
Pass | Construction and land development | Commercial real estate
Total loans
2023	289		289		553
2022	732		732		938
2021	729		729		355
2020	52		52		56
2019	1		1		7
Prior	10		10		4
Revolving loans amortized cost basis	660		660		518
Revolving loans converted to term loans amortized cost basis	67		67		127
Total loans	2,540		2,540		2,558
Pass | Term | Commercial real estate
Total loans
2023	1,108		1,108		1,861
2022	1,360		1,360		2,385
2021	2,271		2,271		1,833
2020	1,460		1,460		1,449
2019	1,113		1,113		804
Prior	1,843		1,843		1,438
Revolving loans amortized cost basis	274		274		238
Revolving loans converted to term loans amortized cost basis	163		163		110
Total loans	9,592		9,592		10,118
Pass | Home equity credit line | Consumer
Total loans
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	3,412		3,412		3,237
Revolving loans converted to term loans amortized cost basis	96		96		97
Total loans	3,508		3,508		3,334
Pass | 1-4 family residential | Consumer
Total loans
2023	697		697		814
2022	842		842		2,264
2021	2,810		2,810		1,823
2020	1,884		1,884		988
2019	944		944		594
Prior	2,264		2,264		1,891
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	9,441		9,441		8,374
Pass | Construction and other consumer real estate | Consumer
Total loans
2023	95		95		212
2022	251		251		1,002
2021	583		583		200
2020	57		57		15
2019	8		8		7
Prior	3		3		6
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	997		997		1,442
Pass | Bankcard and other revolving plans | Consumer
Total loans
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	457		457		471
Revolving loans converted to term loans amortized cost basis	1		1		1
Total loans	458		458		472
Pass | Other | Consumer
Total loans
2023	46		46		66
2022	39		39		37
2021	25		25		18
2020	10		10		6
2019	3		3		4
Prior	2		2		2
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	125		125		133
Special Mention | Commercial and industrial | Commercial
Total loans
2023	16		16		8
2022	12		12		98
2021	38		38		34
2020	18		18		2
2019	3		3		20
Prior	16		16		37
Revolving loans amortized cost basis	72		72		103
Revolving loans converted to term loans amortized cost basis	3		3		0
Total loans	178		178		302
Special Mention | Leasing | Commercial
Total loans
2023	0		0		2
2022	0		0		9
2021	0		0		1
2020	0		0		1
2019	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		13
Special Mention | Owner-occupied | Commercial
Total loans
2023	0		0		2
2022	1		1		5
2021	17		17		17
2020	8		8		5
2019	1		1		17
Prior	11		11		15
Revolving loans amortized cost basis	17		17		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	55		55		61
Special Mention | Municipal | Commercial
Total loans
2023	0		0		7
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	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
2023	13		13		0
2022	0		0		0
2021	9		9		29
2020	37		37		30
2019	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	59		59		59
Special Mention | Term | Commercial real estate
Total loans
2023	72		72		55
2022	14		14		108
2021	64		64		65
2020	30		30		78
2019	46		46		44
Prior	24		24		6
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	250		250		356
Special Mention | Home equity credit line | Consumer
Total loans
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	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
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	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
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	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
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	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
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	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
2023	29		29		11
2022	58		58		18
2021	138		138		7
2020	20		20		2
2019	2		2		19
Prior	22		22		8
Revolving loans amortized cost basis	127		127		99
Revolving loans converted to term loans amortized cost basis	3		3		3
Total loans	399		399		167
Accruing Substandard | Leasing | Commercial
Total loans
2023	1		1		0
2022	3		3		0
2021	8		8		0
2020	2		2		0
2019	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	15		15		0
Accruing Substandard | Owner-occupied | Commercial
Total loans
2023	5		5		10
2022	26		26		31
2021	73		73		29
2020	50		50		21
2019	28		28		16
Prior	142		142		90
Revolving loans amortized cost basis	3		3		2
Revolving loans converted to term loans amortized cost basis	5		5		0
Total loans	332		332		199
Accruing Substandard | Municipal | Commercial
Total loans
2023	0		0		8
2022	13		13		0
2021	0		0		6
2020	0		0		3
2019	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	13		13		19
Accruing Substandard | Construction and land development | Commercial real estate
Total loans
2023	11		11		23
2022	19		19		2
2021	102		102		0
2020	100		100		5
2019	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	232		232		30
Accruing Substandard | Term | Commercial real estate
Total loans
2023	189		189		79
2022	66		66		18
2021	274		274		12
2020	153		153		16
2019	13		13		5
Prior	35		35		24
Revolving loans amortized cost basis	1		1		0
Revolving loans converted to term loans amortized cost basis	10		10		35
Total loans	741		741		189
Accruing Substandard | Home equity credit line | Consumer
Total loans
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	5		5		4
Revolving loans converted to term loans amortized cost basis	0		0		1
Total loans	5		5		5
Accruing Substandard | 1-4 family residential | Consumer
Total loans
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	0		0		0
Prior	1		1		1
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	1		1		1
Accruing Substandard | Construction and other consumer real estate | Consumer
Total loans
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	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
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	2		2		2
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	2		2		2
Accruing Substandard | Other | Consumer
Total loans
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	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
2023	5		5		5
2022	13		13		36
2021	47		47		1
2020	18		18		2
2019	1		1		11
Prior	8		8		1
Revolving loans amortized cost basis	77		77		21
Revolving loans converted to term loans amortized cost basis	4		4		5
Total loans	173		173		82
Nonaccrual | Leasing | Commercial
Total loans
2023	0		0		0
2022	0		0		2
2021	2		2		0
2020	0		0		0
2019	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
2023	5		5		0
2022	1		1		1
2021	1		1		1
2020	1		1		7
2019	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	29		29		20
Nonaccrual | Municipal | Commercial
Total loans
2023	3		3		0
2022	0		0		0
2021	0		0		0
2020	5		5		0
2019	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	11		11		0
Nonaccrual | Construction and land development | Commercial real estate
Total loans
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	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
2023	0		0		0
2022	0		0		26
2021	22		22		0
2020	0		0		0
2019	0		0		3
Prior	11		11		10
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	34		34		0
Total loans	67		67		39
Nonaccrual | Home equity credit line | Consumer
Total loans
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	23		23		15
Revolving loans converted to term loans amortized cost basis	7		7		2
Total loans	30		30		17
Nonaccrual | 1-4 family residential | Consumer
Total loans
2023	0		0		0
2022	3		3		3
2021	8		8		3
2020	7		7		3
2019	2		2		4
Prior	27		27		27
Revolving loans amortized cost basis	0		0		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	47		47		40
Nonaccrual | Construction and other consumer real estate | Consumer
Total loans
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	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
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	0		0		0
2019	0		0		0
Prior	0		0		0
Revolving loans amortized cost basis	1		1		0
Revolving loans converted to term loans amortized cost basis	0		0		0
Total loans	1		1		0
Nonaccrual | Other | Consumer
Total loans
2023	0		0		0
2022	1		1		0
2021	0		0		0
2020	0		0		0
2019	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