LOANS (Past due financing receivables) (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	$ 10,923,532	$ 9,954,572
Nonaccrual	64,560	69,369
30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	8,112	7,026
60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	3,183	336
90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	678	550
Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	11,973	7,912
Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	10,846,999	9,877,291
Commercial and industrial | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	3,278,703	2,645,085
Nonaccrual	25,156	18,228
Commercial and industrial | Commercial and industrial | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	1,406	1,024
Commercial and industrial | Commercial and industrial | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	2,692	183
Commercial and industrial | Commercial and industrial | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	144	541
Commercial and industrial | Commercial and industrial | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	4,242	1,748
Commercial and industrial | Commercial and industrial | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	3,249,305	2,625,109
Commercial and industrial | Paycheck Protection Program ("PPP")
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	13,506	199,883
Nonaccrual	5	0
Commercial and industrial | Paycheck Protection Program ("PPP") | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	763	0
Commercial and industrial | Paycheck Protection Program ("PPP") | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	254	0
Commercial and industrial | Paycheck Protection Program ("PPP") | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	0	0
Commercial and industrial | Paycheck Protection Program ("PPP") | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	1,017	0
Commercial and industrial | Paycheck Protection Program ("PPP") | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	12,484	199,883
Commercial and industrial | Owner occupied commercial real estate
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	2,285,973	2,240,334
Nonaccrual	9,827	11,150
Commercial and industrial | Owner occupied commercial real estate | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	0	130
Commercial and industrial | Owner occupied commercial real estate | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	0	0
Commercial and industrial | Owner occupied commercial real estate | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	0	0
Commercial and industrial | Owner occupied commercial real estate | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	0	130
Commercial and industrial | Owner occupied commercial real estate | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	2,276,146	2,229,054
Commercial and industrial | Non-owner occupied commercial real estate
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	2,219,542	2,010,591
Nonaccrual	11,904	13,316
Commercial and industrial | Non-owner occupied commercial real estate | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	32	3,929
Commercial and industrial | Non-owner occupied commercial real estate | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	0	0
Commercial and industrial | Non-owner occupied commercial real estate | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	0	0
Commercial and industrial | Non-owner occupied commercial real estate | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	32	3,929
Commercial and industrial | Non-owner occupied commercial real estate | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	2,207,606	1,993,346
Commercial and industrial | Real estate construction
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	996,017	856,119
Nonaccrual	2,271	368
Commercial and industrial | Real estate construction | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	4,475	238
Commercial and industrial | Real estate construction | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	0	50
Commercial and industrial | Real estate construction | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	0	0
Commercial and industrial | Real estate construction | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	4,475	288
Commercial and industrial | Real estate construction | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	989,271	855,463
Agricultural and agricultural real estate
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	781,354	753,753
Nonaccrual	8,154	15,686
Agricultural and agricultural real estate | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	0	687
Agricultural and agricultural real estate | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	0	0
Agricultural and agricultural real estate | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	534	0
Agricultural and agricultural real estate | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	534	687
Agricultural and agricultural real estate | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	772,666	737,380
Residential real estate
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	852,928	829,283
Nonaccrual	6,112	9,167
Residential real estate | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	650	767
Residential real estate | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	103	46
Residential real estate | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	0	9
Residential real estate | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	753	822
Residential real estate | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	846,063	819,294
Consumer
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	495,509	419,524
Nonaccrual	1,131	1,454
Consumer | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	786	251
Consumer | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	134	57
Consumer | 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	0	0
Consumer | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	920	308
Consumer | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Gross loans held to maturity	$ 493,458	$ 417,762