SEGMENT INFORMATION (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Information about reportable segments
Net interest income	$ 230,424	$ 209,413	$ 181,684
Provision for loan losses	9,108	4,736	7,205
Noninterest income	99,246	89,222	88,792
Amortization of intangible assets	4,607	4,381	5,957
Other operating expenses	207,150	185,991	170,929
Income before income taxes and equity in undistributed net income of subsidiaries	108,805	103,527	86,385
Assets	7,496,800	6,488,275	5,444,506
Goodwill	369,703	345,050	297,692
Banking [Member]
Information about reportable segments
Net interest income	230,251	209,302	181,582
Provision for loan losses	9,108	4,736	7,205
Noninterest income	50,422	46,921	49,342
Amortization of intangible assets	3,548	3,393	5,081
Other operating expenses	167,332	152,468	140,267
Income before income taxes and equity in undistributed net income of subsidiaries	100,685	95,626	78,371
Assets	7,472,628	6,461,694	5,420,990
Goodwill	359,207	334,554	287,412
Other [Member]
Information about reportable segments
Net interest income	173	111	102
Provision for loan losses	0	0	0
Noninterest income	50,992	44,142	41,066
Amortization of intangible assets	1,059	988	876
Other operating expenses	41,986	35,364	32,278
Income before income taxes and equity in undistributed net income of subsidiaries	8,120	7,901	8,014
Assets	42,506	38,557	33,129
Goodwill	10,496	10,496	10,280
Elimination [Member]
Information about reportable segments
Net interest income	0	0	0
Provision for loan losses	0	0	0
Noninterest income	(2,168)	(1,841)	(1,616)
Amortization of intangible assets	0	0	0
Other operating expenses	(2,168)	(1,841)	(1,616)
Income before income taxes and equity in undistributed net income of subsidiaries	0	0	0
Assets	(18,334)	(11,976)	(9,613)
Goodwill	$ 0	$ 0	$ 0