SEGMENT REPORTING (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Results of Operations [Abstract]
Net interest revenue	$ 453,452	$ 435,682	$ 416,662
Provision for credit losses	4,000	(13,000)
Net interest revenue, after provision for credit losses	449,452	448,682	416,662
Noninterest revenue	279,030	277,968	269,146
Noninterest expense	532,038	539,911	518,406
Income before income taxes	196,444	186,739	167,402
Income tax expense (benefit)	63,716	59,248	50,652
Net Income	132,728	127,491	116,750
Selected Financial Information [Abstract]
Total assets at end of period	14,724,388	13,798,662	13,326,369
Depreciation and amortization	29,264	30,251	31,715
Community Banking [Member]
Results of Operations [Abstract]
Net interest revenue	414,706	397,204	381,467
Provision for credit losses	(641)	(12,859)	(4,757)
Net interest revenue, after provision for credit losses	415,347	410,063	386,224
Noninterest revenue	80,996	82,938	95,752
Noninterest expense	323,939	332,920	329,893
Income before income taxes	172,404	160,081	152,083
Income tax expense (benefit)	57,289	51,186	47,482
Net Income	115,115	108,895	104,601
Selected Financial Information [Abstract]
Total assets at end of period	10,991,377	10,127,861	9,814,879
Depreciation and amortization	21,446	21,874	22,603
Insurance Agencies [Member]
Results of Operations [Abstract]
Net interest revenue	60	100	117
Net interest revenue, after provision for credit losses	60	100	117
Noninterest revenue	116,167	116,780	115,541
Noninterest expense	101,259	101,120	97,620
Income before income taxes	14,968	15,760	18,038
Income tax expense (benefit)	6,031	6,363	7,255
Net Income	8,937	9,397	10,783
Selected Financial Information [Abstract]
Total assets at end of period	213,070	199,668	188,920
Depreciation and amortization	4,281	4,736	5,257
General Corporate and Other [Member]
Results of Operations [Abstract]
Net interest revenue	38,686	38,378	35,078
Provision for credit losses	4,641	(141)	4,757
Net interest revenue, after provision for credit losses	34,045	38,519	30,321
Noninterest revenue	81,867	78,250	57,853
Noninterest expense	106,840	105,871	90,893
Income before income taxes	9,072	10,898	(2,719)
Income tax expense (benefit)	396	1,699	(4,085)
Net Income	8,676	9,199	1,366
Selected Financial Information [Abstract]
Total assets at end of period	3,519,941	3,471,133	3,322,570
Depreciation and amortization	$ 3,537	$ 3,641	$ 3,855