ALLOWANCE FOR LOAN AND LEASE LOSSES - Changes in the Allowance for Loan and Lease Losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Dec. 31, 2017
Allowance for loan and lease losses:
Balance at beginning of period	$ 54,380	$ 56,326	$ 54,021	$ 57,961
Provision for loan and lease losses	3,735	467	6,038	834
Loans charged-off	(5,822)	(4,498)	(9,491)	(7,248)
Recoveries	1,783	2,578	3,508	3,326
Total net charge-offs	4,039	1,920	5,983	3,922
Balance at end of period	54,076	54,873	54,076	54,873
Ending allowance on loans individually evaluated for impairment					$ 366	$ 779
Ending allowance on loans collectively evaluated for impairment					53,710	53,242
Ending allowance for loan and lease losses	54,380	56,326	54,021	54,873	54,076	54,021
Loans and Leases:
Ending balance of loans individually evaluated for impairment					62,301	41,627
Ending balance of loans collectively evaluated for impairment					8,822,280	5,971,556
Loans and Leases Receivable, Net of Deferred Income					8,884,581	6,013,183
Commercial
Allowance for loan and lease losses:
Balance at beginning of period	18,038	17,148	17,598	19,225
Provision for loan and lease losses	3,328	3,537	4,217	2,941
Loans charged-off	(4,356)	(3,065)	(5,241)	(4,808)
Recoveries	518	693	954	955
Total net charge-offs	3,838	2,372	4,287	3,853
Balance at end of period	17,528	18,313	17,528	18,313
Ending allowance on loans individually evaluated for impairment					179	169
Ending allowance on loans collectively evaluated for impairment					17,349	17,429
Ending allowance for loan and lease losses	18,038	17,148	17,528	19,225	17,528	17,598
Loans and Leases:
Ending balance of loans individually evaluated for impairment					11,235	7,331
Ending balance of loans collectively evaluated for impairment					2,429,361	1,905,412
Loans and Leases Receivable, Net of Deferred Income					2,440,596	1,912,743
Lease financing
Allowance for loan and lease losses:
Balance at beginning of period	626	616	675	716
Provision for loan and lease losses	170	(67)	121	(167)
Loans charged-off	0	0	0	0
Recoveries	1	1	1	1
Total net charge-offs	(1)	(1)	(1)	(1)
Balance at end of period	797	550	797	550
Ending allowance on loans individually evaluated for impairment					0	0
Ending allowance on loans collectively evaluated for impairment					797	675
Ending allowance for loan and lease losses	626	616	797	716	797	675
Loans and Leases:
Ending balance of loans individually evaluated for impairment					0	82
Ending balance of loans collectively evaluated for impairment					96,198	89,265
Loans and Leases Receivable, Net of Deferred Income					96,198	89,347
Construction real estate
Allowance for loan and lease losses:
Balance at beginning of period	4,267	3,607	3,577	3,282
Provision for loan and lease losses	(282)	(280)	408	45
Loans charged-off	0	0	0	0
Recoveries	0	89	0	89
Total net charge-offs	0	(89)	0	(89)
Balance at end of period	3,985	3,416	3,985	3,416
Ending allowance on loans individually evaluated for impairment					0	0
Ending allowance on loans collectively evaluated for impairment					3,985	3,577
Ending allowance for loan and lease losses	4,267	3,607	3,985	3,416	3,985	3,577
Loans and Leases:
Ending balance of loans individually evaluated for impairment					24	29
Ending balance of loans collectively evaluated for impairment					555,444	467,701
Loans and Leases Receivable, Net of Deferred Income					555,468	467,730
Commercial real estate
Allowance for loan and lease losses:
Balance at beginning of period	20,321	23,745	20,930	26,540
Provision for loan and lease losses	(619)	(2,941)	196	(5,507)
Loans charged-off	(78)	(485)	(2,254)	(970)
Recoveries	887	1,398	1,639	1,654
Total net charge-offs	(809)	(913)	615	(684)
Balance at end of period	20,511	21,717	20,511	21,717
Ending allowance on loans individually evaluated for impairment					25	448
Ending allowance on loans collectively evaluated for impairment					20,486	20,482
Ending allowance for loan and lease losses	20,321	23,745	20,511	21,717	20,511	20,930
Loans and Leases:
Ending balance of loans individually evaluated for impairment					31,011	21,542
Ending balance of loans collectively evaluated for impairment					3,857,982	2,468,549
Loans and Leases Receivable, Net of Deferred Income					3,888,993	2,490,091
Residential real estate
Allowance for loan and lease losses:
Balance at beginning of period	4,727	5,485	4,683	3,208
Provision for loan and lease losses	(28)	(305)	86	2,024
Loans charged-off	(101)	(223)	(197)	(284)
Recoveries	70	59	96	68
Total net charge-offs	31	164	101	216
Balance at end of period	4,668	5,016	4,668	5,016
Ending allowance on loans individually evaluated for impairment					160	160
Ending allowance on loans collectively evaluated for impairment					4,508	4,523
Ending allowance for loan and lease losses	4,727	5,485	4,668	5,016	4,668	4,683
Loans and Leases:
Ending balance of loans individually evaluated for impairment					13,255	7,932
Ending balance of loans collectively evaluated for impairment					905,649	463,459
Loans and Leases Receivable, Net of Deferred Income					918,904	471,391
Home equity
Allowance for loan and lease losses:
Balance at beginning of period	4,828	3,774	4,935	3,043
Provision for loan and lease losses	171	526	(123)	1,331
Loans charged-off	(385)	(384)	(627)	(564)
Recoveries	187	222	616	328
Total net charge-offs	198	162	11	236
Balance at end of period	4,801	4,138	4,801	4,138
Ending allowance on loans individually evaluated for impairment					2	2
Ending allowance on loans collectively evaluated for impairment					4,799	4,933
Ending allowance for loan and lease losses	4,828	3,774	4,935	3,043	4,801	4,935
Loans and Leases:
Ending balance of loans individually evaluated for impairment					6,472	4,456
Ending balance of loans collectively evaluated for impairment					828,559	489,148
Loans and Leases Receivable, Net of Deferred Income					835,031	493,604
Installment
Allowance for loan and lease losses:
Balance at beginning of period	290	419	307	388
Provision for loan and lease losses	136	19	87	28
Loans charged-off	(218)	(126)	(234)	(175)
Recoveries	82	43	130	114
Total net charge-offs	136	83	104	61
Balance at end of period	290	355	290	355
Ending allowance on loans individually evaluated for impairment					0	0
Ending allowance on loans collectively evaluated for impairment					290	307
Ending allowance for loan and lease losses	290	419	290	355	290	307
Loans and Leases:
Ending balance of loans individually evaluated for impairment					304	255
Ending balance of loans collectively evaluated for impairment					100,422	41,331
Loans and Leases Receivable, Net of Deferred Income					100,726	41,586
Credit card
Allowance for loan and lease losses:
Balance at beginning of period	1,283	1,532	1,316	1,559
Provision for loan and lease losses	859	(22)	1,046	139
Loans charged-off	(684)	(215)	(938)	(447)
Recoveries	38	73	72	117
Total net charge-offs	646	142	(866)	(330)
Balance at end of period	1,496	1,368	1,496	1,368
Ending allowance on loans individually evaluated for impairment					0	0
Ending allowance on loans collectively evaluated for impairment					1,496	1,316
Ending allowance for loan and lease losses	$ 1,283	$ 1,532	$ 1,496	$ 1,368	1,496	1,316
Loans and Leases:
Ending balance of loans individually evaluated for impairment					0	0
Ending balance of loans collectively evaluated for impairment					48,665	46,691
Loans and Leases Receivable, Net of Deferred Income					$ 48,665	$ 46,691