SEGMENT REPORTING (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Results of Operations [Abstract]
Net interest revenue	$ 106,073	$ 101,523
Provision for credit losses	(5,000)
Net interest revenue, after provision for credit losses	111,073	101,523
Noninterest revenue	73,315	66,517
Noninterest expense	136,933	126,707
Income before income taxes	47,455	41,333
Income tax expense (benefit)	15,189	12,889
Net income	32,266	28,444
Selected Financial Information [Abstract]
Total assets at end of period	13,630,322	13,143,555	13,326,369	[1]
Depreciation and amortization	7,755	7,631
Community Banking [Member]
Results of Operations [Abstract]
Net interest revenue	96,867	93,315
Provision for credit losses	(3,967)	1,024
Net interest revenue, after provision for credit losses	100,834	92,291
Noninterest revenue	16,031	23,927
Noninterest expense	86,184	81,467
Income before income taxes	30,681	34,751
Income tax expense (benefit)	10,589	11,182
Net income	20,092	23,569
Selected Financial Information [Abstract]
Total assets at end of period	9,931,629	9,745,120
Depreciation and amortization	5,959	5,216
Insurance Agencies [Member]
Results of Operations [Abstract]
Net interest revenue	32	28
Net interest revenue, after provision for credit losses	32	28
Noninterest revenue	33,198	31,620
Noninterest expense	25,316	24,315
Income before income taxes	7,914	7,333
Income tax expense (benefit)	1,677	2,918
Net income	6,237	4,415
Selected Financial Information [Abstract]
Total assets at end of period	209,434	201,625
Depreciation and amortization	1,265	1,277
General Corporate And Other [Member]
Results of Operations [Abstract]
Net interest revenue	9,174	8,180
Provision for credit losses	(1,033)	(1,024)
Net interest revenue, after provision for credit losses	10,207	9,204
Noninterest revenue	24,086	10,970
Noninterest expense	25,433	20,925
Income before income taxes	8,860	(751)
Income tax expense (benefit)	2,923	(1,211)
Net income	5,937	460
Selected Financial Information [Abstract]
Total assets at end of period	3,489,259	3,196,810
Depreciation and amortization	$ 531	$ 1,138

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