GOODWILL AND IDENTIFIABLE INTANGIBLE ASSETS (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 50,539	$ 50,345
Accumulated Amortization	(41,188)	(38,546)
Net Carrying Amount	9,351	11,799
Estimated aggregate amortization expense [Abstract]
Oct - Dec 2015	788
2016	2,652
2017	1,943
2018	1,453
2019	1,026
Thereafter	1,489
Net Carrying Amount	9,351	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	(32,432)	(30,303)
Net Carrying Amount	7,894	10,023
Estimated aggregate amortization expense [Abstract]
Net Carrying Amount	7,894	10,023
Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	10,213	10,019
Accumulated Amortization	(8,756)	(8,243)
Net Carrying Amount	1,457	1,776
Estimated aggregate amortization expense [Abstract]
Net Carrying Amount	$ 1,457	$ 1,776