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	9 Months Ended
Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Total loans
2024	$ 5,741		$ 5,741		$ 8,155
2023	7,386		7,386		12,553
2022	11,730		11,730		8,774
2021	7,631		7,631		4,982
2020	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
2024	0	$ 1	0	$ 1
2023	1	6	10	12
2022	5	0	13	5
2021	0	0	2	0
2020	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
2024	3,221		3,221		4,492
2023	4,059		4,059		5,770
2022	4,833		4,833		4,436
2021	3,841		3,841		2,336
2020	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
2024	0		0
2023	1		3
2022	5		9
2021	0		2
2020	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
2024	1,682		1,682		2,571
2023	2,191		2,191		3,477
2022	3,471		3,471		2,294
2021	1,832		1,832		1,634
2020	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
2024		0		0
2023		2		2
2022		0		0
2021		0		0
2020		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
2024	838		838		1,092
2023	1,136		1,136		3,306
2022	3,426		3,426		2,044
2021	1,958		1,958		1,012
2020	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
2024	0	0	0	0
2023	0	0	0	0
2022	0	0	0	0
2021	0	0	0	0
2020	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
2024	1,757		1,757		2,678
2023	2,364		2,364		2,572
2022	1,964		1,964		1,246
2021	974		974		645
2020	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
2024	0	1	0	1
2023	1	4	3	10
2022	4	0	8	5
2021	0	0	2	0
2020	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
Owner-occupied \| Commercial
Total loans
2024	944		944		1,092
2023	1,108		1,108		1,982
2022	1,806		1,806		2,067
2021	1,848		1,848		1,035
2020	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
2024	0		0
2023	0		0
2022	1		1
2021	0		0
2020	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
Construction and land development \| Commercial real estate
Total loans
2024	313		313		576
2023	751		751		940
2022	840		840		384
2021	189		189		91
2020	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
2024		0		0
2023		0		0
2022		0		0
2021		0		0
2020		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
2024	1,369		1,369		1,995
2023	1,440		1,440		2,537
2022	2,631		2,631		1,910
2021	1,643		1,643		1,543
2020	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
2024		0	0	0
2023		2	7	2
2022		0	4	0
2021		0	0	0
2020		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
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	3,440		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
2024	0	0	0	0
2023	0	0	0	0
2022	0	0	0	0
2021	0	0	0	0
2020	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
2024	697		697		814
2023	845		845		2,267
2022	2,818		2,818		1,826
2021	1,891		1,891		991
2020	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
2024			0	0
2023			0	0
2022			0	0
2021			0	0
2020			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
Other \| Consumer
Total loans
2024	46		46		66
2023	40		40		37
2022	25		25		18
2021	10		10		6
2020	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
2024			0
2023			0
2022			0
2021			0
2020			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
2024	1,707		1,707		2,654
2023	2,281		2,281		2,420
2022	1,741		1,741		1,204
2021	918		918		639
2020	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 \| Owner-occupied \| Commercial
Total loans
2024	934		934		1,080
2023	1,080		1,080		1,945
2022	1,715		1,715		2,020
2021	1,789		1,789		1,002
2020	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 \| Construction and land development \| Commercial real estate
Total loans
2024	289		289		553
2023	732		732		938
2022	729		729		355
2021	52		52		56
2020	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
2024	1,108		1,108		1,861
2023	1,360		1,360		2,385
2022	2,271		2,271		1,833
2021	1,460		1,460		1,449
2020	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
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	3,412		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
2024	697		697		814
2023	842		842		2,264
2022	2,810		2,810		1,823
2021	1,884		1,884		988
2020	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 \| Other \| Consumer
Total loans
2024	46		46		66
2023	39		39		37
2022	25		25		18
2021	10		10		6
2020	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
2024	16		16		8
2023	12		12		98
2022	38		38		34
2021	18		18		2
2020	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 \| Owner-occupied \| Commercial
Total loans
2024	0		0		2
2023	1		1		5
2022	17		17		17
2021	8		8		5
2020	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 \| Construction and land development \| Commercial real estate
Total loans
2024	13		13		0
2023	0		0		0
2022	9		9		29
2021	37		37		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	59		59		59
Special Mention \| Term \| Commercial real estate
Total loans
2024	72		72		55
2023	14		14		108
2022	64		64		65
2021	30		30		78
2020	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
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 \| 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	29		29		11
2023	58		58		18
2022	138		138		7
2021	20		20		2
2020	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 \| Owner-occupied \| Commercial
Total loans
2024	5		5		10
2023	26		26		31
2022	73		73		29
2021	50		50		21
2020	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 \| Construction and land development \| Commercial real estate
Total loans
2024	11		11		23
2023	19		19		2
2022	102		102		0
2021	100		100		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	232		232		30
Accruing Substandard \| Term \| Commercial real estate
Total loans
2024	189		189		79
2023	66		66		18
2022	274		274		12
2021	153		153		16
2020	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
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	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
2024	0		0		0
2023	0		0		0
2022	0		0		0
2021	0		0		0
2020	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 \| 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	5		5		5
2023	13		13		36
2022	47		47		1
2021	18		18		2
2020	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 \| Owner-occupied \| Commercial
Total loans
2024	5		5		0
2023	1		1		1
2022	1		1		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	29		29		20
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	0		0		26
2022	22		22		0

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