SEGMENT REPORTING (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Results of Operations [Abstract]
Net interest revenue	$ 100,241	$ 103,379	$ 296,532	$ 313,730
Provision for credit losses	500	6,000	7,500	22,000	28,000
Net interest revenue, after provision for credit losses	99,741	97,379	289,032	291,730
Noninterest revenue	62,514	70,420	209,941	209,248
Noninterest expense	129,397	133,788	407,019	405,974
Income before income taxes	32,858	34,011	91,954	95,004
Income tax expense (benefit)	8,001	10,186	25,537	27,689
Net income	24,857	23,825	66,417	67,315
Selected Financial Information [Abstract]
Total assets at end of period	12,916,153	13,235,737	12,916,153	13,235,737	13,397,198	[1]
Depreciation and amortization	7,244	7,658	22,025	22,702
Community Banking [Member]
Results of Operations [Abstract]
Net interest revenue	93,404	96,981	278,373	294,720
Provision for credit losses	95	5,726	6,334	20,242
Net interest revenue, after provision for credit losses	93,309	91,255	272,039	274,478
Noninterest revenue	27,443	28,826	80,670	85,536
Noninterest expense	80,733	84,672	248,494	263,236
Income before income taxes	40,019	35,409	104,215	96,778
Income tax expense (benefit)	10,180	11,150	33,830	30,054
Net income	29,839	24,259	70,385	66,724
Selected Financial Information [Abstract]
Total assets at end of period	9,773,134	10,085,948	9,773,134	10,085,948
Depreciation and amortization	5,658	5,973	17,174	17,835
Insurance Agencies [Member]
Results of Operations [Abstract]
Net interest revenue	41	62	131	211
Net interest revenue, after provision for credit losses	41	62	131	211
Noninterest revenue	24,878	23,461	77,202	69,516
Noninterest expense	21,515	20,721	64,913	58,882
Income before income taxes	3,404	2,802	12,420	10,845
Income tax expense (benefit)	1,542	1,147	3,619	4,370
Net income	1,862	1,655	8,801	6,475
Selected Financial Information [Abstract]
Total assets at end of period	186,003	176,027	186,003	176,027
Depreciation and amortization	858	953	2,637	2,669
General Corporate And Other [Member]
Results of Operations [Abstract]
Net interest revenue	6,796	6,336	18,028	18,799
Provision for credit losses	405	274	1,166	1,758
Net interest revenue, after provision for credit losses	6,391	6,062	16,862	17,041
Noninterest revenue	10,193	18,133	52,069	54,196
Noninterest expense	27,149	28,395	93,612	83,856
Income before income taxes	(10,565)	(4,200)	(24,681)	(12,619)
Income tax expense (benefit)	(3,721)	(2,111)	(11,912)	(6,735)
Net income	(6,844)	(2,089)	(12,769)	(5,884)
Selected Financial Information [Abstract]
Total assets at end of period	2,957,016	2,973,762	2,957,016	2,973,762
Depreciation and amortization	$ 728	$ 732	$ 2,214	$ 2,198

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