SEGMENT REPORTING (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Results of Operations [Abstract]
Net interest revenue	$ 416,662	$ 398,949	$ 414,591
Provision for credit losses		7,500	28,000
Net interest revenue, after provision for credit losses	416,662	391,449	386,591
Noninterest revenue	269,146	275,066	280,149
Noninterest expense	518,406	534,849	549,193
Income before income taxes	167,402	131,666	117,547
Income tax expense (benefit)	50,652	37,551	33,252
Net Income	116,750	94,115	84,295
Selected Financial Information [Abstract]
Total assets at end of period	13,326,369	13,029,733	13,397,198
Depreciation and amortization	31,715	29,523	30,942
Community Banking [Member]
Results of Operations [Abstract]
Net interest revenue	381,604	372,629	389,466
Provision for credit losses	(4,757)	5,824	25,482
Net interest revenue, after provision for credit losses	386,361	366,805	363,984
Noninterest revenue	100,678	108,507	113,613
Noninterest expense	336,341	324,513	351,378
Income before income taxes	150,698	150,799	126,219
Income tax expense (benefit)	48,072	47,454	39,777
Net Income	102,626	103,345	86,442
Selected Financial Information [Abstract]
Total assets at end of period	9,820,238	9,809,428	10,232,036
Depreciation and amortization	24,061	22,912	23,773
Insurance Agencies [Member]
Results of Operations [Abstract]
Net interest revenue	117	165	270
Net interest revenue, after provision for credit losses	117	165	270
Noninterest revenue	115,541	99,103	90,045
Noninterest expense	97,620	86,557	78,799
Income before income taxes	18,038	12,711	11,516
Income tax expense (benefit)	7,255	5,175	4,682
Net Income	10,783	7,536	6,834
Selected Financial Information [Abstract]
Total assets at end of period	188,920	187,424	173,832
Depreciation and amortization	5,257	3,655	3,616
General Corporate and Other [Member]
Results of Operations [Abstract]
Net interest revenue	34,941	26,155	24,855
Provision for credit losses	4,757	1,676	2,518
Net interest revenue, after provision for credit losses	30,184	24,479	22,337
Noninterest revenue	52,927	67,456	76,491
Noninterest expense	84,445	123,779	119,016
Income before income taxes	(1,334)	(31,844)	(20,188)
Income tax expense (benefit)	(4,675)	(15,078)	(11,207)
Net Income	3,341	(16,766)	(8,981)
Selected Financial Information [Abstract]
Total assets at end of period	3,317,211	3,032,881	2,991,330
Depreciation and amortization	$ 2,397	$ 2,956	$ 3,553