SEGMENT INFORMATION (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Information about reportable segments
Net interest income	$ 57,771	$ 54,187	$ 111,680	$ 99,710
Provision for loan losses	2,155	1,050	3,799	2,100
Noninterest income	23,696	22,751	47,164	43,593
Gain on investment securities & debt extinguishments	0	14	0	14
Amortization of intangible assets	1,045	1,189	2,131	2,090
Other operating expenses	48,325	49,937	96,642	92,352
Income before income taxes	29,942	24,776	56,272	46,775
Assets	7,166,331	6,390,485	7,166,331	6,390,485	6,488,275
Goodwill	345,050	345,915	345,050	345,915	345,050
Banking [Member]
Information about reportable segments
Net interest income	57,730	54,162	111,599	99,663
Provision for loan losses	2,155	1,050	3,799	2,100
Noninterest income	11,929	12,115	23,292	22,594
Gain on investment securities & debt extinguishments		14		14
Amortization of intangible assets	774	921	1,578	1,621
Other operating expenses	38,588	41,778	77,106	76,327
Income before income taxes	28,142	22,542	52,408	42,223
Assets	7,141,681	6,365,080	7,141,681	6,365,080
Goodwill	334,554	335,634	334,554	335,634
Other [Member]
Information about reportable segments
Net interest income	41	25	81	47
Provision for loan losses	0	0	0	0
Noninterest income	12,281	11,081	24,961	21,924
Gain on investment securities & debt extinguishments		0		0
Amortization of intangible assets	271	268	553	469
Other operating expenses	10,251	8,604	20,625	16,950
Income before income taxes	1,800	2,234	3,864	4,552
Assets	39,632	36,688	39,632	36,688
Goodwill	10,496	10,281	10,496	10,281
Elimination [Member]
Information about reportable segments
Net interest income	0	0	0	0
Provision for loan losses	0	0	0	0
Noninterest income	(514)	(445)	(1,089)	(925)
Gain on investment securities & debt extinguishments		0		0
Amortization of intangible assets	0	0	0	0
Other operating expenses	(514)	(445)	(1,089)	(925)
Income before income taxes	0	0	0	0
Assets	(14,982)	(11,283)	(14,982)	(11,283)
Goodwill	$ 0	$ 0	$ 0	$ 0