CREDIT QUALITY ASSESSMENT - Credit Quality of Loan Portfolio (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Financing Receivable, Past Due [Line Items]
Total loans	$ 11,491,921	$ 11,366,989
Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	11,366,652	11,275,142
Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	124,870	91,485
Loans greater than 90 days past due	399	362
Total loans	125,269	91,847
Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	11,337,639	11,248,749
30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	26,598	23,732
60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	2,415	2,661
Commercial investor real estate
Financing Receivable, Past Due [Line Items]
Total loans	4,868,467	5,104,425
Commercial owner-occupied real estate
Financing Receivable, Past Due [Line Items]
Total loans	1,737,327	1,755,235
Commercial AD&C
Financing Receivable, Past Due [Line Items]
Total loans	1,255,609	988,967
Residential mortgage
Financing Receivable, Past Due [Line Items]
Total loans	1,529,786	1,474,521
Residential construction
Financing Receivable, Past Due [Line Items]
Total loans	53,639	121,419
Commercial real estate: | Commercial investor real estate
Financing Receivable, Past Due [Line Items]
Total loans	4,868,467	5,104,425
Commercial real estate: | Commercial investor real estate | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	4,810,889	5,045,767
Commercial real estate: | Commercial investor real estate | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	57,578	58,658
Loans greater than 90 days past due	0	0
Total loans	57,578	58,658
Commercial real estate: | Commercial investor real estate | Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	4,804,222	5,044,647
Commercial real estate: | Commercial investor real estate | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	5,882	1,120
Commercial real estate: | Commercial investor real estate | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	785	0
Commercial real estate: | Commercial owner-occupied real estate
Financing Receivable, Past Due [Line Items]
Total loans	1,737,327	1,755,235
Commercial real estate: | Commercial owner-occupied real estate | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,727,688	1,750,595
Commercial real estate: | Commercial owner-occupied real estate | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	9,639	4,640
Loans greater than 90 days past due	0	0
Total loans	9,639	4,640
Commercial real estate: | Commercial owner-occupied real estate | Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,726,532	1,748,449
Commercial real estate: | Commercial owner-occupied real estate | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,156	2,056
Commercial real estate: | Commercial owner-occupied real estate | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	0	90
Commercial real estate: | Commercial AD&C
Financing Receivable, Past Due [Line Items]
Total loans	1,255,609	988,967
Commercial real estate: | Commercial AD&C | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,223,793	987,708
Commercial real estate: | Commercial AD&C | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	31,816	1,259
Loans greater than 90 days past due	0	0
Total loans	31,816	1,259
Commercial real estate: | Commercial AD&C | Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,221,424	986,859
Commercial real estate: | Commercial AD&C | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	2,369	849
Commercial real estate: | Commercial AD&C | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	0	0
Commercial Business
Financing Receivable, Past Due [Line Items]
Total loans	9,482,329	9,353,507
Commercial Business | Commercial business
Financing Receivable, Past Due [Line Items]
Total loans	1,620,926	1,504,880
Commercial Business | Commercial business | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,611,882	1,494,809
Commercial Business | Commercial business | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	9,044	10,051
Loans greater than 90 days past due	0	20
Total loans	9,044	10,071
Commercial Business | Commercial business | Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,610,802	1,494,426
Commercial Business | Commercial business | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,030	383
Commercial Business | Commercial business | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	50	0
Residential real estate: | Residential mortgage
Financing Receivable, Past Due [Line Items]
Total loans	1,529,786	1,474,521
Residential real estate: | Residential mortgage | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,517,391	1,461,847
Residential real estate: | Residential mortgage | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	11,996	12,332
Loans greater than 90 days past due	399	342
Total loans	12,395	12,674
Residential real estate: | Residential mortgage | Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,503,638	1,445,785
Residential real estate: | Residential mortgage | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	12,826	14,026
Residential real estate: | Residential mortgage | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	927	2,036
Residential real estate: | Residential construction
Financing Receivable, Past Due [Line Items]
Total loans	53,639	121,419
Residential real estate: | Residential construction | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	53,100	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	51,100	118,976
Residential real estate: | Residential construction | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	2,000	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	426,167	417,542
Consumer | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	421,909	413,440
Consumer | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	4,258	4,102
Loans greater than 90 days past due	0	0
Total loans	4,258	4,102
Consumer | Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	419,921	409,607
Consumer | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,335	3,298
Consumer | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	$ 653	$ 535