SEGMENT INFORMATION (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Information about reportable segments
Net interest income	$ 58,425	$ 53,909
Provision for loan losses	1,393	1,644
Noninterest income	26,109	23,468
Amortization of intangible assets	1,179	1,086
Other operating expenses	53,373	48,317
Income before income taxes	28,589	26,330
Assets	7,221,073	6,912,458	7,496,800
Goodwill	369,703	345,050	369,703
Banking [Member]
Information about reportable segments
Net interest income	58,374	53,869
Provision for loan losses	1,393	1,644
Noninterest income	12,641	11,363
Amortization of intangible assets	937	804
Other operating expenses	43,231	38,517
Income before income taxes	25,454	24,267
Assets	7,196,214	6,887,276
Goodwill	359,207	334,554
Other [Member]
Information about reportable segments
Net interest income	51	40
Provision for loan losses	0	0
Noninterest income	14,075	12,679
Amortization of intangible assets	242	282
Other operating expenses	10,749	10,374
Income before income taxes	3,135	2,063
Assets	45,135	39,412
Goodwill	10,496	10,496
Eliminations [Member]
Information about reportable segments
Net interest income	0	0
Provision for loan losses	0	0
Noninterest income	(607)	(574)
Amortization of intangible assets	0	0
Other operating expenses	(607)	(574)
Income before income taxes	0	0
Assets	(20,276)	(14,230)
Goodwill	$ 0	$ 0