SEGMENT INFORMATION (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Information about reportable segments
Net interest income	$ 58,432	$ 57,771	$ 116,857	$ 111,680
Provision for loan losses	1,321	2,155	2,714	3,799
Noninterest income	27,098	23,696	53,207	47,164
Amortization of intangible assets	1,140	1,045	2,319	2,131
Other operating expenses	53,236	48,325	106,609	96,642
Income before income taxes	29,833	29,942	58,422	56,272
Assets	7,020,716	7,166,331	7,020,716	7,166,331	7,496,800
Goodwill	369,703	345,050	369,703	345,050	369,703
Eliminations [Member]
Information about reportable segments
Net interest income	0	0	0	0
Provision for loan losses	0	0	0	0
Noninterest income	(584)	(514)	(1,190)	(1,089)
Amortization of intangible assets	0	0	0	0
Other operating expenses	(584)	(514)	(1,190)	(1,089)
Income before income taxes	0	0	0	0
Assets	(12,649)	(14,982)	(12,649)	(14,982)
Goodwill	0	0	0	0
Banking [Member]
Information about reportable segments
Net interest income	58,379	57,730	116,753	111,599
Provision for loan losses	1,321	2,155	2,714	3,799
Noninterest income	13,654	11,929	26,295	23,292
Amortization of intangible assets	908	774	1,846	1,578
Other operating expenses	42,946	38,588	86,177	77,106
Income before income taxes	26,858	28,142	52,311	52,408
Assets	6,995,501	7,141,681	6,995,501	7,141,681
Goodwill	359,207	334,554	359,207	334,554
Other [Member]
Information about reportable segments
Net interest income	53	41	104	81
Provision for loan losses	0	0	0	0
Noninterest income	14,028	12,281	28,102	24,961
Amortization of intangible assets	232	271	473	553
Other operating expenses	10,874	10,251	21,622	20,625
Income before income taxes	2,975	1,800	6,111	3,864
Assets	37,864	39,632	37,864	39,632
Goodwill	$ 10,496	$ 10,496	$ 10,496	$ 10,496