LOANS AND LEASES - Loan Delinquency, including Nonaccrual Loans (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	$ 44,838	$ 51,946
Current		9,849,024
Total loans and leases	9,511,510	9,900,970
> 90 days past due and still accruing	155	169
Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	9,544	17,837
Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	1,800	1,577
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	33,494	32,532
Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current	9,466,672
Commercial
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	9,438	8,393
Current		2,999,116
Total loans and leases	2,701,203	3,007,509
> 90 days past due and still accruing	0	0
Commercial | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	150	6,532
Commercial | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	300	0
Commercial | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	8,988	1,861
Commercial | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current	2,691,765
Lease financing
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	15	0
Current		72,987
Total loans and leases	68,229	72,987
> 90 days past due and still accruing	0	0
Lease financing | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	0	0
Lease financing | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	0	0
Lease financing | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	15	0
Lease financing | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current	68,214
Construction real estate
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	0	0
Current		636,096
Total loans and leases	630,329	636,096
> 90 days past due and still accruing	0	0
Construction real estate | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	0	0
Construction real estate | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	0	0
Construction real estate | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	0	0
Construction real estate | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current	630,329
Commercial real estate - investor
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	26,845	24,558
Current		3,219,982
Total loans and leases	3,318,836	3,244,540
> 90 days past due and still accruing	0	0
Commercial real estate - investor | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	5,788	136
Commercial real estate - investor | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	0	0
Commercial real estate - investor | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	21,057	24,422
Commercial real estate - investor | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current	3,291,991
Commercial real estate-owner
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	479	7,054
Current		1,056,264
Total loans and leases	1,013,725	1,063,318
> 90 days past due and still accruing	0	0
Commercial real estate-owner | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	162	6,480
Commercial real estate-owner | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	245	174
Commercial real estate-owner | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	72	400
Commercial real estate-owner | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current	1,013,246
Residential real estate
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	4,941	6,866
Current		996,220
Total loans and leases	932,112	1,003,086
> 90 days past due and still accruing	0	0
Residential real estate | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	2,351	2,809
Residential real estate | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	793	370
Residential real estate | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	1,797	3,687
Residential real estate | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current	927,171
Home equity
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	2,654	4,255
Current		738,844
Total loans and leases	711,756	743,099
> 90 days past due and still accruing	0	0
Home equity | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	864	1,483
Home equity | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	406	835
Home equity | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	1,384	1,937
Home equity | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current	709,102
Installment
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	59	180
Current		81,670
Total loans and leases	89,143	81,850
> 90 days past due and still accruing	0	0
Installment | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	50	94
Installment | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	0	35
Installment | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	9	51
Installment | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current	89,084
Credit card
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	407	640
Current		47,845
Total loans and leases	46,177	48,485
> 90 days past due and still accruing	155	169
Credit card | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	179	303
Credit card | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	56	163
Credit card | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss, Noncurrent	172	$ 174
Credit card | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current	$ 45,770