CREDIT QUALITY ASSESSMENT - Credit Quality of Loan Portfolio (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Financing Receivable, Past Due [Line Items]
Total loans	$ 11,483,921	$ 11,366,989
Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	11,390,932	11,275,142
Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	92,650	91,485
Loans greater than 90 days past due	339	362
Total loans	92,989	91,847
Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	11,368,157	11,248,749
30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	19,658	23,732
60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	3,117	2,661
Commercial investor real estate
Financing Receivable, Past Due [Line Items]
Total loans	4,933,329	5,104,425
Commercial owner-occupied real estate
Financing Receivable, Past Due [Line Items]
Total loans	1,747,708	1,755,235
Commercial AD&C
Financing Receivable, Past Due [Line Items]
Total loans	1,184,296	988,967
Residential mortgage
Financing Receivable, Past Due [Line Items]
Total loans	1,521,890	1,474,521
Residential construction
Financing Receivable, Past Due [Line Items]
Total loans	78,027	121,419
Commercial real estate: | Commercial investor real estate
Financing Receivable, Past Due [Line Items]
Total loans	4,933,329	5,104,425
Commercial real estate: | Commercial investor real estate | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	4,877,831	5,045,767
Commercial real estate: | Commercial investor real estate | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	55,498	58,658
Loans greater than 90 days past due	0	0
Total loans	55,498	58,658
Commercial real estate: | Commercial investor real estate | Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	4,873,362	5,044,647
Commercial real estate: | Commercial investor real estate | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	3,219	1,120
Commercial real estate: | Commercial investor real estate | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,250	0
Commercial real estate: | Commercial owner-occupied real estate
Financing Receivable, Past Due [Line Items]
Total loans	1,747,708	1,755,235
Commercial real estate: | Commercial owner-occupied real estate | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,738,305	1,750,595
Commercial real estate: | Commercial owner-occupied real estate | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	9,403	4,640
Loans greater than 90 days past due	0	0
Total loans	9,403	4,640
Commercial real estate: | Commercial owner-occupied real estate | Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,736,874	1,748,449
Commercial real estate: | Commercial owner-occupied real estate | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,160	2,056
Commercial real estate: | Commercial owner-occupied real estate | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	271	90
Commercial real estate: | Commercial AD&C
Financing Receivable, Past Due [Line Items]
Total loans	1,184,296	988,967
Commercial real estate: | Commercial AD&C | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,182,169	987,708
Commercial real estate: | Commercial AD&C | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	2,127	1,259
Loans greater than 90 days past due	0	0
Total loans	2,127	1,259
Commercial real estate: | Commercial AD&C | Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,181,407	986,859
Commercial real estate: | Commercial AD&C | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	0	849
Commercial real estate: | Commercial AD&C | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	762	0
Commercial Business
Financing Receivable, Past Due [Line Items]
Total loans	9,466,843	9,353,507
Commercial Business | Commercial business
Financing Receivable, Past Due [Line Items]
Total loans	1,601,510	1,504,880
Commercial Business | Commercial business | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,593,055	1,494,809
Commercial Business | Commercial business | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	8,455	10,051
Loans greater than 90 days past due	0	20
Total loans	8,455	10,071
Commercial Business | Commercial business | Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,590,529	1,494,426
Commercial Business | Commercial business | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	2,339	383
Commercial Business | Commercial business | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	187	0
Residential real estate: | Residential mortgage
Financing Receivable, Past Due [Line Items]
Total loans	1,521,890	1,474,521
Residential real estate: | Residential mortgage | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,509,323	1,461,847
Residential real estate: | Residential mortgage | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	12,228	12,332
Loans greater than 90 days past due	339	342
Total loans	12,567	12,674
Residential real estate: | Residential mortgage | Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,497,566	1,445,785
Residential real estate: | Residential mortgage | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	11,165	14,026
Residential real estate: | Residential mortgage | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	592	2,036
Residential real estate: | Residential construction
Financing Receivable, Past Due [Line Items]
Total loans	78,027	121,419
Residential real estate: | Residential construction | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	77,488	120,976
Residential real estate: | Residential construction | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	539	443
Loans greater than 90 days past due	0	0
Total loans	539	443
Residential real estate: | Residential construction | Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	76,749	118,976
Residential real estate: | Residential construction | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	739	2,000
Residential real estate: | Residential construction | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	0	0
Consumer
Financing Receivable, Past Due [Line Items]
Total loans	417,161	417,542
Consumer | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	412,761	413,440
Consumer | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	4,400	4,102
Loans greater than 90 days past due	0	0
Total loans	4,400	4,102
Consumer | Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	411,670	409,607
Consumer | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,036	3,298
Consumer | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	$ 55	$ 535