SEGMENT REPORTING (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Results of Operations [Abstract]
Net interest revenue	$ 103,379	$ 108,075	$ 313,730	$ 327,424
Provision for credit losses	6,000	25,112	22,000	110,831	130,081
Net interest revenue after provision for credit losses	97,379	82,963	291,730	216,593
Noninterest revenue	70,420	62,055	209,248	205,510
Noninterest expense	133,788	130,698	405,974	397,777
Income before income taxes	34,011	14,320	95,004	24,326
Income tax expense (benefit)	10,186	2,386	27,689	60
Net income	23,825	11,934	67,315	24,266
Selected Financial Information [Abstract]
Total assets at end of period	13,235,737	13,198,518	13,235,737	13,198,518	12,995,851	[1]
Depreciation and amortization	7,658	7,987	22,702	24,460
Community Banking [Member]
Results of Operations [Abstract]
Net interest revenue	105,075	101,092	319,376	306,635
Provision for credit losses	5,726	23,416	20,242	109,191
Net interest revenue after provision for credit losses	99,349	77,676	299,134	197,444
Noninterest revenue	31,026	30,940	91,956	99,845
Noninterest expense	87,039	83,028	270,155	257,683
Income before income taxes	43,336	25,588	120,935	39,606
Income tax expense (benefit)	14,107	5,669	39,128	13,313
Net income	29,229	19,919	81,807	26,293
Selected Financial Information [Abstract]
Total assets at end of period	10,693,813	10,305,304	10,693,813	10,305,304
Depreciation and amortization	6,012	5,967	17,945	18,348
Insurance Agencies [Member]
Results of Operations [Abstract]
Net interest revenue	62	79	211	258
Provision for credit losses	0	0	0	0
Net interest revenue after provision for credit losses	62	79	211	258
Noninterest revenue	23,461	22,009	69,516	67,436
Noninterest expense	20,721	19,032	58,882	56,095
Income before income taxes	2,802	3,056	10,845	11,599
Income tax expense (benefit)	1,147	1,238	4,370	4,639
Net income	1,655	1,818	6,475	6,960
Selected Financial Information [Abstract]
Total assets at end of period	176,027	166,572	176,027	166,572
Depreciation and amortization	953	947	2,669	2,893
General Corporate and Other [Member]
Results of Operations [Abstract]
Net interest revenue	(1,758)	6,904	(5,857)	20,531
Provision for credit losses	274	1,696	1,758	1,640
Net interest revenue after provision for credit losses	(2,032)	5,208	(7,615)	18,891
Noninterest revenue	15,933	9,106	47,776	38,229
Noninterest expense	26,028	28,638	76,937	83,999
Income before income taxes	(12,127)	(14,324)	(36,776)	(26,879)
Income tax expense (benefit)	(5,068)	(4,521)	(15,809)	(17,892)
Net income	(7,059)	(9,803)	(20,967)	(8,987)
Selected Financial Information [Abstract]
Total assets at end of period	2,365,897	2,726,642	2,365,897	2,726,642
Depreciation and amortization	$ 693	$ 1,073	$ 2,088	$ 3,219

[1] Derived from audited financial statements.