SEGMENT REPORTING (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014	[1]
Results of Operations [Abstract]
Net interest revenue	$ 107,309	$ 103,081	$ 213,382	$ 204,604
Provision for credit losses	(5,000)		(10,000)
Net interest revenue, after provision for credit losses	112,309	103,081	223,382	204,604
Noninterest revenue	74,314	69,838	147,629	136,355
Noninterest expense	128,177	127,954	265,110	254,661
Income before income taxes	58,446	44,965	105,901	86,298
Income tax expense (benefit)	18,733	14,097	33,922	26,986
Net income	39,713	30,868	71,979	59,312
Selected Financial Information [Abstract]
Total assets at end of period	13,634,931	12,985,887	13,634,931	12,985,887	$ 13,326,369
Depreciation and amortization	7,749	8,144	15,504	15,775
Community Banking [Member]
Results of Operations [Abstract]
Net interest revenue	97,679	94,425	194,518	187,588
Provision for credit losses	(5,831)	(548)	(9,798)	476
Net interest revenue, after provision for credit losses	103,510	94,973	204,316	187,112
Noninterest revenue	16,311	19,113	32,307	38,483
Noninterest expense	72,041	74,453	153,806	151,088
Income before income taxes	47,780	39,633	82,817	74,507
Income tax expense (benefit)	15,856	12,952	26,347	24,182
Net income	31,924	26,681	56,470	50,325
Selected Financial Information [Abstract]
Total assets at end of period	9,867,629	9,550,723	9,867,629	9,550,723
Depreciation and amortization	5,551	5,833	11,089	11,229
Insurance Agencies [Member]
Results of Operations [Abstract]
Net interest revenue	35	30	67	58
Net interest revenue, after provision for credit losses	35	30	67	58
Noninterest revenue	29,280	28,872	62,478	60,493
Noninterest expense	25,296	24,371	50,612	48,686
Income before income taxes	4,019	4,531	11,933	11,865
Income tax expense (benefit)	1,609	1,807	4,755	4,725
Net income	2,410	2,724	7,178	7,140
Selected Financial Information [Abstract]
Total assets at end of period	211,142	205,756	211,142	205,756
Depreciation and amortization	1,232	1,346	2,497	2,623
General Corporate And Other [Member]
Results of Operations [Abstract]
Net interest revenue	9,595	8,626	18,797	16,649
Provision for credit losses	831	548	(202)	(476)
Net interest revenue, after provision for credit losses	8,764	8,078	18,999	17,434
Noninterest revenue	28,723	21,853	52,844	37,379
Noninterest expense	30,840	29,130	60,692	54,887
Income before income taxes	6,647	801	11,151	(74)
Income tax expense (benefit)	1,268	(662)	2,820	(1,921)
Net income	5,379	1,463	8,331	1,847
Selected Financial Information [Abstract]
Total assets at end of period	3,556,160	3,229,408	3,556,160	3,229,408
Depreciation and amortization	$ 966	$ 342	$ 1,918	$ 1,923

[1] Derived from audited financial statements.See accompanying notes to consolidated financial statements.