LOANS (Loans by credit quality indicator) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Dec. 31, 2023
Amortized Cost Basis of Term Loans by Year of Origination
Year One	$ 949,219		$ 949,219	$ 2,247,517
Year Two	1,979,645		1,979,645	3,073,040
Year Three	2,750,210		2,750,210	2,172,951
Year Four	1,853,644		1,853,644	802,905
Year Five	669,565		669,565	720,479
Year Six and Prior	1,520,404		1,520,404	1,148,381
Revolving	1,718,230		1,718,230	1,903,372
Total	11,440,917		11,440,917	12,068,645
Charge-offs
Year One			12	531
Year Two			135	1,953
Year Three			23,982	958
Year Four			1,075	1,527
Year Five			3,575	981
Year Six and Prior			2,881	2,272
Revolving			11,958	11,392
Total charge-offs	32,137	$ 3,964	43,618	19,614
Pass
Amortized Cost Basis of Term Loans by Year of Origination
Year One	908,544		908,544	2,085,645
Year Two	1,812,190		1,812,190	2,901,425
Year Three	2,417,749		2,417,749	2,128,112
Year Four	1,736,848		1,736,848	773,698
Year Five	641,810		641,810	651,885
Year Six and Prior	1,354,260		1,354,260	1,012,958
Revolving	1,573,281		1,573,281	1,838,626
Total	10,444,682		10,444,682	11,392,349
Watch
Amortized Cost Basis of Term Loans by Year of Origination
Year One	31,876		31,876	103,921
Year Two	129,495		129,495	130,920
Year Three	219,918		219,918	33,047
Year Four	99,824		99,824	11,501
Year Five	10,505		10,505	38,127
Year Six and Prior	81,764		81,764	73,492
Revolving	118,488		118,488	31,236
Total	691,870		691,870	422,244
Substandard
Amortized Cost Basis of Term Loans by Year of Origination
Year One	8,799		8,799	57,951
Year Two	37,960		37,960	40,695
Year Three	112,543		112,543	11,792
Year Four	16,972		16,972	17,706
Year Five	17,250		17,250	30,467
Year Six and Prior	84,380		84,380	61,931
Revolving	26,461		26,461	33,510
Total	304,365		304,365	254,052
Commercial and industrial | Commercial and industrial
Amortized Cost Basis of Term Loans by Year of Origination
Year One	435,752		435,752	648,895
Year Two	466,380		466,380	811,664
Year Three	629,843		629,843	336,793
Year Four	258,381		258,381	196,484
Year Five	160,845		160,845	99,388
Year Six and Prior	353,007		353,007	338,217
Revolving	1,198,885		1,198,885	1,220,606
Total	3,503,093		3,503,093	3,652,047
Charge-offs
Year One			0	245
Year Two			28	794
Year Three			14,391	680
Year Four			813	1,425
Year Five			3,299	563
Year Six and Prior			2,358	1,949
Revolving			9,328	2,966
Total charge-offs	22,006	1,344	30,217	8,622
Commercial and industrial | Commercial and industrial | Pass
Amortized Cost Basis of Term Loans by Year of Origination
Year One	414,619		414,619	608,030
Year Two	408,974		408,974	779,218
Year Three	566,449		566,449	333,900
Year Four	244,760		244,760	187,406
Year Five	153,020		153,020	78,455
Year Six and Prior	343,559		343,559	327,775
Revolving	1,068,024		1,068,024	1,159,397
Total	3,199,405		3,199,405	3,474,181
Commercial and industrial | Commercial and industrial | Watch
Amortized Cost Basis of Term Loans by Year of Origination
Year One	13,954		13,954	20,694
Year Two	54,206		54,206	19,788
Year Three	48,302		48,302	257
Year Four	12,535		12,535	3,631
Year Five	2,173		2,173	2,398
Year Six and Prior	6,583		6,583	2,953
Revolving	105,711		105,711	28,749
Total	243,464		243,464	78,470
Commercial and industrial | Commercial and industrial | Substandard
Amortized Cost Basis of Term Loans by Year of Origination
Year One	7,179		7,179	20,171
Year Two	3,200		3,200	12,658
Year Three	15,092		15,092	2,636
Year Four	1,086		1,086	5,447
Year Five	5,652		5,652	18,535
Year Six and Prior	2,865		2,865	7,489
Revolving	25,150		25,150	32,460
Total	60,224		60,224	99,396
Commercial and industrial | Paycheck Protection Program ("PPP")
Amortized Cost Basis of Term Loans by Year of Origination
Year One	0		0	0
Year Two	0		0	0
Year Three	0		0	2,727
Year Four	1,560		1,560	50
Year Five	22		22	0
Year Six and Prior	0		0	0
Revolving	0		0	0
Total	1,582		1,582	2,777
Charge-offs
Year One			0	0
Year Two			0	0
Year Three			0	0
Year Four			0	0
Year Five			0	0
Year Six and Prior			0	0
Revolving			0	0
Total charge-offs			0	0
Commercial and industrial | Paycheck Protection Program ("PPP") | Pass
Amortized Cost Basis of Term Loans by Year of Origination
Year One	0		0	0
Year Two	0		0	0
Year Three	0		0	2,591
Year Four	1,402		1,402	50
Year Five	22		22	0
Year Six and Prior	0		0	0
Revolving	0		0	0
Total	1,424		1,424	2,641
Commercial and industrial | Paycheck Protection Program ("PPP") | Watch
Amortized Cost Basis of Term Loans by Year of Origination
Year One	0		0	0
Year Two	0		0	0
Year Three	0		0	89
Year Four	158		158	0
Year Five	0		0	0
Year Six and Prior	0		0	0
Revolving	0		0	0
Total	158		158	89
Commercial and industrial | Paycheck Protection Program ("PPP") | Substandard
Amortized Cost Basis of Term Loans by Year of Origination
Year One	0		0	0
Year Two	0		0	0
Year Three	0		0	47
Year Four	0		0	0
Year Five	0		0	0
Year Six and Prior	0		0	0
Revolving	0		0	0
Total	0		0	47
Commercial and industrial | Owner occupied commercial real estate
Amortized Cost Basis of Term Loans by Year of Origination
Year One	124,397		124,397	483,639
Year Two	426,882		426,882	584,334
Year Three	579,037		579,037	815,360
Year Four	702,894		702,894	239,528
Year Five	213,470		213,470	239,910
Year Six and Prior	401,401		401,401	234,332
Revolving	41,616		41,616	41,072
Total	2,489,697		2,489,697	2,638,175
Charge-offs
Year One			0	0
Year Two			0	802
Year Three			87	0
Year Four			0	5
Year Five			247	0
Year Six and Prior			88	63
Revolving			0	0
Total charge-offs	25	0	422	870
Commercial and industrial | Owner occupied commercial real estate | Pass
Amortized Cost Basis of Term Loans by Year of Origination
Year One	118,081		118,081	443,683
Year Two	397,969		397,969	547,898
Year Three	480,966		480,966	799,978
Year Four	698,709		698,709	225,257
Year Five	200,112		200,112	225,405
Year Six and Prior	345,593		345,593	224,608
Revolving	38,270		38,270	41,072
Total	2,279,700		2,279,700	2,507,901
Commercial and industrial | Owner occupied commercial real estate | Watch
Amortized Cost Basis of Term Loans by Year of Origination
Year One	6,316		6,316	8,052
Year Two	5,595		5,595	25,947
Year Three	67,107		67,107	13,114
Year Four	1,421		1,421	2,662
Year Five	2,811		2,811	8,115
Year Six and Prior	41,544		41,544	7,553
Revolving	3,346		3,346	0
Total	128,140		128,140	65,443
Commercial and industrial | Owner occupied commercial real estate | Substandard
Amortized Cost Basis of Term Loans by Year of Origination
Year One	0		0	31,904
Year Two	23,318		23,318	10,489
Year Three	30,964		30,964	2,268
Year Four	2,764		2,764	11,609
Year Five	10,547		10,547	6,390
Year Six and Prior	14,264		14,264	2,171
Revolving	0		0	0
Total	81,857		81,857	64,831
Commercial and industrial | Non-owner occupied commercial real estate
Amortized Cost Basis of Term Loans by Year of Origination
Year One	124,399		124,399	557,126
Year Two	527,674		527,674	692,427
Year Three	687,591		687,591	433,048
Year Four	410,166		410,166	207,164
Year Five	172,789		172,789	294,124
Year Six and Prior	516,043		516,043	342,844
Revolving	16,734		16,734	26,978
Total	2,455,396		2,455,396	2,553,711
Charge-offs
Year One			0	0
Year Two			0	52
Year Three			0	0
Year Four			0	29
Year Five			0	399
Year Six and Prior			0	147
Revolving			0	0
Total charge-offs	0	607	0	627
Commercial and industrial | Non-owner occupied commercial real estate | Pass
Amortized Cost Basis of Term Loans by Year of Origination
Year One	112,658		112,658	480,683
Year Two	462,424		462,424	656,824
Year Three	626,077		626,077	423,420
Year Four	381,385		381,385	203,330
Year Five	169,602		169,602	262,541
Year Six and Prior	438,111		438,111	251,499
Revolving	16,734		16,734	26,978
Total	2,206,991		2,206,991	2,305,275
Commercial and industrial | Non-owner occupied commercial real estate | Watch
Amortized Cost Basis of Term Loans by Year of Origination
Year One	11,021		11,021	71,400
Year Two	65,250		65,250	34,651
Year Three	61,380		61,380	8,237
Year Four	20,632		20,632	3,834
Year Five	2,825		2,825	27,345
Year Six and Prior	27,428		27,428	57,083
Revolving	0		0	0
Total	188,536		188,536	202,550
Commercial and industrial | Non-owner occupied commercial real estate | Substandard
Amortized Cost Basis of Term Loans by Year of Origination
Year One	720		720	5,043
Year Two	0		0	952
Year Three	134		134	1,391
Year Four	8,149		8,149	0
Year Five	362		362	4,238
Year Six and Prior	50,504		50,504	34,262
Revolving	0		0	0
Total	59,869		59,869	45,886
Commercial and industrial | Real estate construction
Amortized Cost Basis of Term Loans by Year of Origination
Year One	126,889		126,889	284,148
Year Two	353,246		353,246	510,388
Year Three	472,305		472,305	186,022
Year Four	144,275		144,275	10,068
Year Five	7,237		7,237	11,048
Year Six and Prior	9,034		9,034	3,470
Revolving	6,936		6,936	6,572
Total	1,119,922		1,119,922	1,011,716
Charge-offs
Year One			0	284
Year Two			0	0
Year Three			0	0
Year Four			0	32
Year Five			0	0
Year Six and Prior			0	0
Revolving			0	0
Total charge-offs	0	0	0	316
Commercial and industrial | Real estate construction | Pass
Amortized Cost Basis of Term Loans by Year of Origination
Year One	126,889		126,889	283,519
Year Two	343,871		343,871	468,646
Year Three	374,867		374,867	176,604
Year Four	81,057		81,057	9,889
Year Five	7,059		7,059	11,048
Year Six and Prior	8,969		8,969	3,405
Revolving	6,850		6,850	6,486
Total	949,562		949,562	959,597
Commercial and industrial | Real estate construction | Watch
Amortized Cost Basis of Term Loans by Year of Origination
Year One	0		0	629
Year Two	0		0	33,220
Year Three	40,782		40,782	9,418
Year Four	63,207		63,207	72
Year Five	166		166	0
Year Six and Prior	0		0	65
Revolving	0		0	0
Total	104,155		104,155	43,404
Commercial and industrial | Real estate construction | Substandard
Amortized Cost Basis of Term Loans by Year of Origination
Year One	0		0	0
Year Two	9,375		9,375	8,522
Year Three	56,656		56,656	0
Year Four	11		11	107
Year Five	12		12	0
Year Six and Prior	65		65	0
Revolving	86		86	86
Total	66,205		66,205	8,715
Agricultural and agricultural real estate
Amortized Cost Basis of Term Loans by Year of Origination
Year One	75,317		75,317	154,922
Year Two	112,252		112,252	232,248
Year Three	184,725		184,725	116,740
Year Four	94,382		94,382	67,632
Year Five	48,267		48,267	29,172
Year Six and Prior	62,066		62,066	56,603
Revolving	124,202		124,202	261,867
Total	701,211		701,211	919,184
Charge-offs
Year One			0	0
Year Two			12	0
Year Three			9,321	0
Year Four			17	9
Year Five			12	0
Year Six and Prior			167	1
Revolving			648	5,309
Total charge-offs	9,302	10	10,177	5,319
Agricultural and agricultural real estate | Pass
Amortized Cost Basis of Term Loans by Year of Origination
Year One	74,398		74,398	152,665
Year Two	109,176		109,176	208,375
Year Three	175,308		175,308	114,798
Year Four	92,490		92,490	67,006
Year Five	48,115		48,115	28,247
Year Six and Prior	49,247		49,247	43,663
Revolving	117,190		117,190	260,941
Total	665,924		665,924	875,695
Agricultural and agricultural real estate | Watch
Amortized Cost Basis of Term Loans by Year of Origination
Year One	188		188	2,245
Year Two	1,940		1,940	16,257
Year Three	807		807	293
Year Four	273		273	622
Year Five	31		31	70
Year Six and Prior	802		802	349
Revolving	7,012		7,012	427
Total	11,053		11,053	20,263
Agricultural and agricultural real estate | Substandard
Amortized Cost Basis of Term Loans by Year of Origination
Year One	731		731	12
Year Two	1,136		1,136	7,616
Year Three	8,610		8,610	1,649
Year Four	1,619		1,619	4
Year Five	121		121	855
Year Six and Prior	12,017		12,017	12,591
Revolving	0		0	499
Total	24,234		24,234	23,226
Residential real estate
Amortized Cost Basis of Term Loans by Year of Origination
Year One	34,903		34,903	72,382
Year Two	59,015		59,015	178,687
Year Three	147,296		147,296	245,707
Year Four	214,006		214,006	74,152
Year Five	63,945		63,945	42,974
Year Six and Prior	170,247		170,247	164,393
Revolving	18,572		18,572	19,534
Total	707,984		707,984	797,829
Charge-offs
Year One			0	0
Year Two			0	59
Year Three			0	124
Year Four			0	0
Year Five			0	0
Year Six and Prior			182	0
Revolving			0	0
Total charge-offs	182	0	182	183
Residential real estate | Pass
Amortized Cost Basis of Term Loans by Year of Origination
Year One	34,859		34,859	71,470
Year Two	56,401		56,401	177,564
Year Three	145,289		145,289	241,362
Year Four	209,388		209,388	73,029
Year Five	61,100		61,100	42,526
Year Six and Prior	162,320		162,320	155,899
Revolving	18,401		18,401	19,534
Total	687,758		687,758	781,384
Residential real estate | Watch
Amortized Cost Basis of Term Loans by Year of Origination
Year One	44		44	171
Year Two	1,841		1,841	973
Year Three	1,174		1,174	945
Year Four	1,457		1,457	659
Year Five	2,479		2,479	158
Year Six and Prior	4,545		4,545	4,845
Revolving	171		171	0
Total	11,711		11,711	7,751
Residential real estate | Substandard
Amortized Cost Basis of Term Loans by Year of Origination
Year One	0		0	741
Year Two	773		773	150
Year Three	833		833	3,400
Year Four	3,161		3,161	464
Year Five	366		366	290
Year Six and Prior	3,382		3,382	3,649
Revolving	0		0	0
Total	8,515		8,515	8,694
Consumer
Amortized Cost Basis of Term Loans by Year of Origination
Year One	27,562		27,562	46,405
Year Two	34,196		34,196	63,292
Year Three	49,413		49,413	36,554
Year Four	27,980		27,980	7,827
Year Five	2,990		2,990	3,863
Year Six and Prior	8,606		8,606	8,522
Revolving	311,285		311,285	326,743
Total	462,032		462,032	493,206
Charge-offs
Year One			12	2
Year Two			95	246
Year Three			183	154
Year Four			245	27
Year Five			17	19
Year Six and Prior			86	112
Revolving			1,982	3,117
Total charge-offs	622	$ 2,003	2,620	3,677
Consumer | Pass
Amortized Cost Basis of Term Loans by Year of Origination
Year One	27,040		27,040	45,595
Year Two	33,375		33,375	62,900
Year Three	48,793		48,793	35,459
Year Four	27,657		27,657	7,731
Year Five	2,780		2,780	3,663
Year Six and Prior	6,461		6,461	6,109
Revolving	307,812		307,812	324,218
Total	453,918		453,918	485,675
Consumer | Watch
Amortized Cost Basis of Term Loans by Year of Origination
Year One	353		353	730
Year Two	663		663	84
Year Three	366		366	694
Year Four	141		141	21
Year Five	20		20	41
Year Six and Prior	862		862	644
Revolving	2,248		2,248	2,060
Total	4,653		4,653	4,274
Consumer | Substandard
Amortized Cost Basis of Term Loans by Year of Origination
Year One	169		169	80
Year Two	158		158	308
Year Three	254		254	401
Year Four	182		182	75
Year Five	190		190	159
Year Six and Prior	1,283		1,283	1,769
Revolving	1,225		1,225	465
Total	$ 3,461		$ 3,461	$ 3,257