GOODWILL AND IDENTIFIABLE INTANGIBLE ASSETS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 50,345	$ 50,345
Accumulated Amortization	(39,465)	(38,546)
Net Carrying Amount	10,880	11,799
Estimated aggregate amortization expense [Abstract]
Apr - Dec 2015	2,489
2016	2,612
2017	1,908
2018	1,424
2019	1,002
Thereafter	1,445
Net Carrying Amount	10,880	11,799
Components of goodwill [Abstract]
Goodwill	379,998	379,998
Goodwill, Activity	0
Accumulated impairment	(4,824)	(4,824)
Accumulated impairment, Activity	0
Goodwill, net	375,174	375,174	375,174
Goodwill, net, Activity	0
Core Deposit Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	40,326	40,326
Accumulated Amortization	(31,042)	(30,303)
Net Carrying Amount	9,284	10,023
Estimated aggregate amortization expense [Abstract]
Net Carrying Amount	9,284	10,023
Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	10,019	10,019
Accumulated Amortization	(8,423)	(8,243)
Net Carrying Amount	1,596	1,776
Estimated aggregate amortization expense [Abstract]
Net Carrying Amount	$ 1,596	$ 1,776