Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Segment	Jun. 30, 2013
Segment Reporting Information [Line Items]
Number of segments in which the business operates			3
Net interest income	$ 105,288	$ 99,228	$ 200,192	$ 188,203
Provision for loan losses, net	4,135	(6,398)	3,393	(9,236)
Noninterest income	44,140	43,714	88,218	88,053
Noninterest expense	102,761	107,195	204,379	209,340
Income before income taxes	42,532	42,145	80,638	76,152
Income taxes	9,635	11,024	18,738	20,165
Net Income	32,897	31,121	61,900	55,987
Selected Financial Information [Abstract]
Average assets	11,971,023	11,782,650	11,945,064	11,294,023
Depreciation and amortization	9,200	9,937	17,956	18,317
General Banking [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	105,064	99,046	199,750	187,780
Provision for loan losses, net	4,135	(6,398)	3,393	(9,236)
Noninterest income	28,139	28,688	56,022	58,909
Noninterest expense	89,545	94,502	178,132	185,347
Income before income taxes	39,523	39,630	74,247	70,578
Income taxes	8,563	10,105	16,477	18,176
Net Income	30,960	29,525	57,770	52,402
Selected Financial Information [Abstract]
Average assets	11,898,471	11,716,531	11,873,885	11,228,269
Depreciation and amortization	8,918	9,637	17,393	17,719
Wealth Management [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	134	112	282	288
Noninterest income	7,698	7,005	15,795	13,879
Noninterest expense	6,620	6,645	13,054	11,936
Income before income taxes	1,212	472	3,023	2,231
Income taxes	402	147	1,002	732
Net Income	810	325	2,021	1,499
Selected Financial Information [Abstract]
Average assets	2,037	174	4,472	152
Depreciation and amortization	49	40	95	79
Insurance [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	90	70	160	135
Noninterest income	8,303	8,021	16,401	15,265
Noninterest expense	6,596	6,048	13,193	12,057
Income before income taxes	1,797	2,043	3,368	3,343
Income taxes	670	772	1,259	1,257
Net Income	1,127	1,271	2,109	2,086
Selected Financial Information [Abstract]
Average assets	70,515	65,945	66,707	65,602
Depreciation and amortization	$ 233	$ 260	$ 468	$ 519