LOANS AND LEASES - Loan Delinquency, including Nonaccrual Loans (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	$ 60,537	$ 70,190
Current	8,838,528	8,657,704
Loans and Leases Receivable, Gross	8,899,065	8,727,894
Purchased impaired loans	81,721	96,320
Total loans and leases	8,980,786	8,824,214
> 90 days past due and still accruing	107	63
Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	24,662	37,266
Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	6,462	5,536
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	29,413	27,388
Commercial
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	29,727	20,833
Current	2,513,194	2,488,450
Loans and Leases Receivable, Gross	2,542,921	2,509,283
Purchased impaired loans	5,076	5,378
Total loans and leases	2,547,997	2,514,661
> 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, Past Due	16,749	13,369
Commercial | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	1,093	41
Commercial | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	11,885	7,423
Lease financing
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	0	352
Current	90,638	93,063
Loans and Leases Receivable, Gross	90,638	93,415
Purchased impaired loans	0	0
Total loans and leases	90,638	93,415
> 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, Past Due	0	352
Lease financing | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	0	0
Lease financing | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	0	0
Construction real estate
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	595	0
Current	496,903	548,687
Loans and Leases Receivable, Gross	497,498	548,687
Purchased impaired loans	185	248
Total loans and leases	497,683	548,935
> 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, Past Due	0	0
Construction real estate | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	595	0
Construction real estate | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	0	0
Commercial real estate
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	13,312	20,081
Current	3,847,576	3,682,455
Loans and Leases Receivable, Gross	3,860,888	3,702,536
Purchased impaired loans	42,766	52,145
Total loans and leases	3,903,654	3,754,681
> 90 days past due and still accruing	0	0
Commercial real estate | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	1,925	6,279
Commercial real estate | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	1,345	1,158
Commercial real estate | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	10,042	12,644
Residential real estate
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	8,419	18,571
Current	976,923	902,404
Loans and Leases Receivable, Gross	985,342	920,975
Purchased impaired loans	30,478	34,671
Total loans and leases	1,015,820	955,646
> 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, Past Due	2,313	11,060
Residential real estate | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	1,393	2,976
Residential real estate | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	4,713	4,535
Home equity
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	7,446	9,051
Current	776,821	804,835
Loans and Leases Receivable, Gross	784,267	813,886
Purchased impaired loans	2,872	3,396
Total loans and leases	787,139	817,282
> 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, Past Due	3,160	5,245
Home equity | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	1,683	1,228
Home equity | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	2,603	2,578
Installment
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	435	602
Current	88,370	92,128
Loans and Leases Receivable, Gross	88,805	92,730
Purchased impaired loans	344	482
Total loans and leases	89,149	93,212
> 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, Past Due	205	420
Installment | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	167	37
Installment | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	63	145
Credit card
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	603	700
Current	48,103	45,682
Loans and Leases Receivable, Gross	48,706	46,382
Purchased impaired loans	0	0
Total loans and leases	48,706	46,382
> 90 days past due and still accruing	107	63
Credit card | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	310	541
Credit card | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	186	96
Credit card | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	$ 107	$ 63