CREDIT QUALITY ASSESSMENT - Credit Quality of Loan Portfolio, New (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Total loans	$ 11,395,241	$ 11,396,706
Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	11,347,994	11,357,347
Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	43,678	34,782
Loans greater than 90 days past due	3,569	1,002
Restructured loans (1)	0	3,575
Total loans	47,247	39,359
Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	11,320,797	11,312,130
30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	20,008	32,576
60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	7,189	12,641
Commercial investor real estate
Financing Receivable, Past Due [Line Items]
Total loans	5,167,456	5,130,094
Commercial owner-occupied real estate
Financing Receivable, Past Due [Line Items]
Total loans	1,769,928	1,775,037
Commercial AD&C
Financing Receivable, Past Due [Line Items]
Total loans	1,046,665	1,090,028
Residential mortgage
Financing Receivable, Past Due [Line Items]
Total loans	1,328,524	1,287,933
Residential construction
Financing Receivable, Past Due [Line Items]
Total loans	223,456	224,772
Commercial real estate: | Commercial investor real estate
Financing Receivable, Past Due [Line Items]
Total loans	5,167,456	5,130,094
Commercial real estate: | Commercial investor real estate | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	5,151,790	5,120,151
Commercial real estate: | Commercial investor real estate | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	15,451	9,943
Loans greater than 90 days past due	215	0
Restructured loans (1)	0	0
Total loans	15,666	9,943
Commercial real estate: | Commercial investor real estate | Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	5,150,572	5,104,204
Commercial real estate: | Commercial investor real estate | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	945	9,735
Commercial real estate: | Commercial investor real estate | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	273	6,212
Commercial real estate: | Commercial owner-occupied real estate
Financing Receivable, Past Due [Line Items]
Total loans	1,769,928	1,775,037
Commercial real estate: | Commercial owner-occupied real estate | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,764,979	1,768,882
Commercial real estate: | Commercial owner-occupied real estate | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	4,949	5,019
Loans greater than 90 days past due	0	0
Restructured loans (1)	0	1,136
Total loans	4,949	6,155
Commercial real estate: | Commercial owner-occupied real estate | Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,761,671	1,767,875
Commercial real estate: | Commercial owner-occupied real estate | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	0	1,007
Commercial real estate: | Commercial owner-occupied real estate | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	3,308	0
Commercial real estate: | Commercial AD&C
Financing Receivable, Past Due [Line Items]
Total loans	1,046,665	1,090,028
Commercial real estate: | Commercial AD&C | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,046,665	1,090,028
Commercial real estate: | Commercial AD&C | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	0	0
Loans greater than 90 days past due	0	0
Restructured loans (1)	0	0
Total loans	0	0
Commercial real estate: | Commercial AD&C | Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,043,979	1,090,028
Commercial real estate: | Commercial AD&C | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	2,240	0
Commercial real estate: | Commercial AD&C | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	446	0
Commercial Business
Financing Receivable, Past Due [Line Items]
Total loans	9,421,527	9,451,044
Commercial Business | Commercial business
Financing Receivable, Past Due [Line Items]
Total loans	1,437,478	1,455,885
Commercial Business | Commercial business | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,425,033	1,446,609
Commercial Business | Commercial business | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	9,443	7,322
Loans greater than 90 days past due	3,002	1,002
Restructured loans (1)	0	952
Total loans	12,445	9,276
Commercial Business | Commercial business | Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,424,758	1,443,012
Commercial Business | Commercial business | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	154	3,556
Commercial Business | Commercial business | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	121	41
Residential real estate: | Residential mortgage
Financing Receivable, Past Due [Line Items]
Total loans	1,328,524	1,287,933
Residential real estate: | Residential mortgage | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,319,237	1,279,007
Residential real estate: | Residential mortgage | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	8,935	7,439
Loans greater than 90 days past due	352	0
Restructured loans (1)	0	1,487
Total loans	9,287	8,926
Residential real estate: | Residential mortgage | Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,304,124	1,261,878
Residential real estate: | Residential mortgage | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	13,402	11,307
Residential real estate: | Residential mortgage | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	1,711	5,822
Residential real estate: | Residential construction
Financing Receivable, Past Due [Line Items]
Total loans	223,456	224,772
Residential real estate: | Residential construction | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	223,456	224,772
Residential real estate: | Residential construction | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	0	0
Loans greater than 90 days past due	0	0
Restructured loans (1)	0	0
Total loans	0	0
Residential real estate: | Residential construction | Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	222,387	222,144
Residential real estate: | Residential construction | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	739	2,628
Residential real estate: | Residential construction | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	330	0
Consumer
Financing Receivable, Past Due [Line Items]
Total loans	421,734	432,957
Consumer | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	416,834	427,898
Consumer | Non-performing loans:
Financing Receivable, Past Due [Line Items]
Non-accrual loans	4,900	5,059
Loans greater than 90 days past due	0	0
Restructured loans (1)	0	0
Total loans	4,900	5,059
Consumer | Current | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	413,306	422,989
Consumer | 30-59 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	2,528	4,343
Consumer | 60-89 days | Performing loans:
Financing Receivable, Past Due [Line Items]
Total loans	$ 1,000	$ 566