GOODWILL AND IDENTIFIABLE INTANGIBLE ASSETS (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 50,345	$ 49,767
Accumulated Amortization	(38,546)	(34,259)
Net Carrying Amount	11,799	15,508
Finite-lived intangible assets, future amortization expense [Abstract]
2015	3,408
2016	2,612
2017	1,908
2018	1,424
2019	1,002
Thereafter	1,445
Net Carrying Amount	11,799	15,508
Components of goodwill [Abstract]
Goodwill	379,998	379,815		374,527
Goodwill, activity	183	5,288
Accumulated impairment	(4,824)	(4,824)	(4,824)
Accumulated impairment, activity	0	0
Goodwill, net	375,174	374,991		369,703
Goodwill, net, activity	183	5,288
Key economic assumptions used to estimate the value of the MSRs [Abstract]
Weighted-average contractual life	19 years 7 months 6 days	19 years 2 months 12 days
Weighted-average constant prepayment rate (CPR) (in hundredths)	12.80%	18.00%
Weighted-average discount rate (in hundredths)	3.20%	4.50%
Core Deposit Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	40,326	40,326	40,326
Accumulated Amortization	(30,303)	(26,866)	(30,303)
Net Carrying Amount	10,023	13,460	10,023
Finite-lived intangible assets, future amortization expense [Abstract]
Net Carrying Amount	10,023	13,460	10,023
Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	10,019	9,441	10,019
Accumulated Amortization	(8,243)	(7,393)	(8,243)
Net Carrying Amount	1,776	2,048	1,776
Finite-lived intangible assets, future amortization expense [Abstract]
Net Carrying Amount	1,776	2,048	1,776
Mortgage Servicing Rights [Member]
Servicing Asset at Fair Value, Amount [Roll Forward]
Carrying value before valuation allowance at beginning of period	1,218	1,458
Additions	315	289
Amortization	(444)	(529)
Carrying value before valuation allowance at end of period	1,089	1,218
Valuation Allowance for Impairment of Recognized Servicing Assets [Roll Forward]
Valuation allowance balance at beginning of period	0	(430)
Impairment charges	0	(111)
Impairment recoveries	0	541
Valuation allowance balance at end of period	0	0
Net carrying value at end of period	1,089	1,218
Fair value of MSRs at end of period	1,616	1,495
Principal balance of loans sold during the year	25,728	25,179
Principal balance of loans serviced for others	302,895	322,030
Custodial escrow balances maintained in connection with loans serviced for others	$ 4,320	$ 4,519