ALLOWANCE FOR LOAN AND LEASE LOSSES - Changes in the Allowance for Loan and Lease Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision for Loan and Lease Losses	$ 5,228	$ 3,238	$ 25,969	$ 9,276
Loans and Leases Receivable, Allowance	56,552	57,715	56,552	57,715	$ 61,549	$ 56,542	$ 54,076	$ 54,021
Allowance for loan and lease losses:
Allowance for Loan and Lease Losses, Write-offs	(11,659)	(2,063)	(29,406)	(11,554)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	1,434	2,464	3,447	5,972
Allowance for Loan and Lease Losses Write-offs, Net	10,225	(401)	25,959	5,582
Ending allowance on loans individually evaluated for impairment	279		279			1,160
Ending allowance on loans collectively evaluated for impairment	56,273		56,273			55,382
Loans and Leases:
Ending balance of loans individually evaluated for impairment	79,143		79,143			86,809
Ending balance of loans collectively evaluated for impairment	8,984,535		8,984,535			8,737,405
Loans and Leases Receivable, Net of Deferred Income	9,063,678		9,063,678			8,824,214
Impaired Financing Receivable, Related Allowance	56,552		56,552			56,542
Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision for Loan and Lease Losses	2,654	2,035	22,164	6,252
Loans and Leases Receivable, Allowance	18,240	19,958	18,240	19,958	24,586	18,746	17,528	17,598
Allowance for loan and lease losses:
Allowance for Loan and Lease Losses, Write-offs	(9,556)	(232)	(23,757)	(5,473)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	556	627	1,087	1,581
Allowance for Loan and Lease Losses Write-offs, Net	9,000	(395)	22,670	3,892
Ending allowance on loans individually evaluated for impairment	91		91			667
Ending allowance on loans collectively evaluated for impairment	18,149		18,149			18,079
Loans and Leases:
Ending balance of loans individually evaluated for impairment	36,917		36,917			37,633
Ending balance of loans collectively evaluated for impairment	2,433,100		2,433,100			2,477,028
Loans and Leases Receivable, Net of Deferred Income	2,470,017		2,470,017			2,514,661
Impaired Financing Receivable, Related Allowance	18,240		18,240			18,746
Lease financing
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision for Loan and Lease Losses	(388)	287	(25)	408
Loans and Leases Receivable, Allowance	1,005	1,084	1,005	1,084	1,393	1,130	797	675
Allowance for loan and lease losses:
Allowance for Loan and Lease Losses, Write-offs	0	0	(100)	0
Allowance for Loan and Lease Loss, Recovery of Bad Debts	0	0	0	1
Allowance for Loan and Lease Losses Write-offs, Net	0	0	100	(1)
Ending allowance on loans individually evaluated for impairment	43		43			0
Ending allowance on loans collectively evaluated for impairment	962		962			1,130
Loans and Leases:
Ending balance of loans individually evaluated for impairment	284		284			22
Ending balance of loans collectively evaluated for impairment	92,332		92,332			93,393
Loans and Leases Receivable, Net of Deferred Income	92,616		92,616			93,415
Impaired Financing Receivable, Related Allowance	1,005		1,005			1,130
Construction real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision for Loan and Lease Losses	(152)	(114)	(714)	294
Loans and Leases Receivable, Allowance	2,767	4,017	2,767	4,017	2,919	3,413	3,985	3,577
Allowance for loan and lease losses:
Allowance for Loan and Lease Losses, Write-offs	0	0	0	0
Allowance for Loan and Lease Loss, Recovery of Bad Debts	0	146	68	146
Allowance for Loan and Lease Losses Write-offs, Net	0	(146)	(68)	(146)
Ending allowance on loans individually evaluated for impairment	0		0			0
Ending allowance on loans collectively evaluated for impairment	2,767		2,767			3,413
Loans and Leases:
Ending balance of loans individually evaluated for impairment	5		5			9
Ending balance of loans collectively evaluated for impairment	515,955		515,955			548,926
Loans and Leases Receivable, Net of Deferred Income	515,960		515,960			548,935
Impaired Financing Receivable, Related Allowance	2,767		2,767			3,413
Commercial real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision for Loan and Lease Losses	1,684	959	1,966	1,155
Loans and Leases Receivable, Allowance	21,853	21,354	21,853	21,354	20,357	21,048	20,511	20,930
Allowance for loan and lease losses:
Allowance for Loan and Lease Losses, Write-offs	(535)	(902)	(1,835)	(3,156)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	347	786	674	2,425
Allowance for Loan and Lease Losses Write-offs, Net	188	116	1,161	731
Ending allowance on loans individually evaluated for impairment	127		127			461
Ending allowance on loans collectively evaluated for impairment	21,726		21,726			20,587
Loans and Leases:
Ending balance of loans individually evaluated for impairment	19,756		19,756			25,022
Ending balance of loans collectively evaluated for impairment	3,996,152		3,996,152			3,729,659
Loans and Leases Receivable, Net of Deferred Income	4,015,908		4,015,908			3,754,681
Impaired Financing Receivable, Related Allowance	21,853		21,853			21,048
Residential real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision for Loan and Lease Losses	702	50	841	136
Loans and Leases Receivable, Allowance	5,496	4,644	5,496	4,644	5,008	4,964	4,668	4,683
Allowance for loan and lease losses:
Allowance for Loan and Lease Losses, Write-offs	(278)	(145)	(510)	(342)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	64	71	201	167
Allowance for Loan and Lease Losses Write-offs, Net	214	74	309	175
Ending allowance on loans individually evaluated for impairment	18		18			32
Ending allowance on loans collectively evaluated for impairment	5,478		5,478			4,932
Loans and Leases:
Ending balance of loans individually evaluated for impairment	16,133		16,133			17,598
Ending balance of loans collectively evaluated for impairment	1,038,874		1,038,874			938,048
Loans and Leases Receivable, Net of Deferred Income	1,055,007		1,055,007			955,646
Impaired Financing Receivable, Related Allowance	5,496		5,496			4,964
Home equity
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision for Loan and Lease Losses	68	63	427	(60)
Loans and Leases Receivable, Allowance	5,083	4,932	5,083	4,932	5,307	5,348	4,801	4,935
Allowance for loan and lease losses:
Allowance for Loan and Lease Losses, Write-offs	(627)	(351)	(1,784)	(978)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	335	419	1,092	1,035
Allowance for Loan and Lease Losses Write-offs, Net	292	(68)	692	(57)
Ending allowance on loans individually evaluated for impairment	0		0			0
Ending allowance on loans collectively evaluated for impairment	5,083		5,083			5,348
Loans and Leases:
Ending balance of loans individually evaluated for impairment	5,944		5,944			6,351
Ending balance of loans collectively evaluated for impairment	770,941		770,941			810,931
Loans and Leases Receivable, Net of Deferred Income	776,885		776,885			817,282
Impaired Financing Receivable, Related Allowance	5,083		5,083			5,348
Installment
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision for Loan and Lease Losses	(2)	(288)	49	(201)
Loans and Leases Receivable, Allowance	421	310	421	310	395	362	290	307
Allowance for loan and lease losses:
Allowance for Loan and Lease Losses, Write-offs	(65)	(43)	(192)	(277)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	93	351	202	481
Allowance for Loan and Lease Losses Write-offs, Net	(28)	(308)	(10)	(204)
Ending allowance on loans individually evaluated for impairment	0		0			0
Loans and Leases:
Loans and Leases Receivable, Net of Deferred Income	1,969,177		1,969,177			1,912,522
Installment
Allowance for loan and lease losses:
Ending allowance on loans individually evaluated for impairment	0		0			0
Ending allowance on loans collectively evaluated for impairment	421		421			362
Loans and Leases:
Ending balance of loans individually evaluated for impairment	104		104			174
Ending balance of loans collectively evaluated for impairment	88,171		88,171			93,038
Loans and Leases Receivable, Net of Deferred Income	88,275		88,275			93,212
Impaired Financing Receivable, Related Allowance	421		421			362
Credit card
Financing Receivable, Allowance for Credit Loss [Line Items]
Provision for Loan and Lease Losses	662	246	1,261	1,292
Loans and Leases Receivable, Allowance	1,687	1,416	1,687	1,416	$ 1,584	1,531	$ 1,496	$ 1,316
Allowance for loan and lease losses:
Allowance for Loan and Lease Losses, Write-offs	(598)	(390)	(1,228)	(1,328)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	39	64	123	136
Allowance for Loan and Lease Losses Write-offs, Net	(559)	$ (326)	(1,105)	$ (1,192)
Ending allowance on loans individually evaluated for impairment	0		0			0
Ending allowance on loans collectively evaluated for impairment	1,687		1,687			1,531
Loans and Leases:
Ending balance of loans individually evaluated for impairment	0		0			0
Ending balance of loans collectively evaluated for impairment	49,010		49,010			46,382
Loans and Leases Receivable, Net of Deferred Income	49,010		49,010			46,382
Impaired Financing Receivable, Related Allowance	$ 1,687		$ 1,687			$ 1,531