LOANS AND LEASES - Loan Delinquency, including Nonaccrual Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	$ 46,195	$ 70,190
Current	8,941,040	8,657,704
Loans and Leases Receivable, Gross	8,987,235	8,727,894
Purchased impaired loans	76,443	96,320
Total loans and leases	9,063,678	8,824,214
> 90 days past due and still accruing	287	63
Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	15,889	37,266
Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	5,931	5,536
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	24,375	27,388
Commercial
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	14,335	20,833
Current	2,452,565	2,488,450
Loans and Leases Receivable, Gross	2,466,900	2,509,283
Purchased impaired loans	3,117	5,378
Total loans and leases	2,470,017	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	9,709	13,369
Commercial | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	358	41
Commercial | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	4,268	7,423
Lease financing
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	1,782	352
Current	90,834	93,063
Loans and Leases Receivable, Gross	92,616	93,415
Purchased impaired loans	0	0
Total loans and leases	92,616	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	1,782	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	0	0
Current	515,935	548,687
Loans and Leases Receivable, Gross	515,935	548,687
Purchased impaired loans	25	248
Total loans and leases	515,960	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	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, Past Due	0	0
Commercial real estate
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	13,202	20,081
Current	3,961,547	3,682,455
Loans and Leases Receivable, Gross	3,974,749	3,702,536
Purchased impaired loans	41,159	52,145
Total loans and leases	4,015,908	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	637	6,279
Commercial real estate | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	1,267	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	11,298	12,644
Residential real estate
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	9,275	18,571
Current	1,016,632	902,404
Loans and Leases Receivable, Gross	1,025,907	920,975
Purchased impaired loans	29,100	34,671
Total loans and leases	1,055,007	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	809	11,060
Residential real estate | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	2,784	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	5,682	4,535
Home equity
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	6,615	9,051
Current	767,525	804,835
Loans and Leases Receivable, Gross	774,140	813,886
Purchased impaired loans	2,745	3,396
Total loans and leases	776,885	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	2,426	5,245
Home equity | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	1,308	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	2,881	2,578
Installment
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	340	602
Current	87,638	92,128
Loans and Leases Receivable, Gross	87,978	92,730
Purchased impaired loans	297	482
Total loans and leases	88,275	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	240	420
Installment | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	29	37
Installment | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	71	145
Credit card
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	646	700
Current	48,364	45,682
Loans and Leases Receivable, Gross	49,010	46,382
Purchased impaired loans	0	0
Total loans and leases	49,010	46,382
> 90 days past due and still accruing	287	63
Credit card | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	286	541
Credit card | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	185	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	$ 175	$ 63