Segment Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) Segment	Jun. 30, 2014 USD ($)
Segment Reporting Information [Line Items]
Number of segments in which the business operates | Segment			3
Net interest income	$ 96,949	$ 105,288	$ 194,341	$ 200,192
Provision for loan losses, net	1,858	4,135	3,990	3,393
Noninterest income	45,543	44,140	87,906	88,218
Noninterest expense	100,266	102,761	199,482	204,379
Income before income taxes	40,368	42,532	78,775	80,638
Income taxes	9,766	9,635	19,025	18,738
Net Income	30,602	32,897	59,750	61,900
Selected Financial Information [Abstract]
Average assets	12,113,259	11,971,023	12,119,248	11,945,064
Depreciation and amortization	9,449	9,200	18,529	17,956
General Banking [Member] | Reportable Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	96,815	105,064	194,075	199,750
Provision for loan losses, net	1,858	4,135	3,990	3,393
Noninterest income	28,417	28,139	54,157	56,022
Noninterest expense	86,843	89,545	172,360	178,132
Income before income taxes	36,531	39,523	71,882	74,247
Income taxes	8,297	8,563	16,381	16,477
Net Income	28,234	30,960	55,501	57,770
Selected Financial Information [Abstract]
Average assets	12,036,687	11,898,424	12,054,143	11,876,198
Depreciation and amortization	9,172	8,918	18,047	17,393
Wealth Management [Member] | Reportable Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	48	134	103	282
Noninterest income	7,722	7,698	15,729	15,795
Noninterest expense	6,408	6,620	13,178	13,054
Income before income taxes	1,362	1,212	2,654	3,023
Income taxes	502	402	1,015	1,002
Net Income	860	810	1,639	2,021
Selected Financial Information [Abstract]
Average assets	4,256	2,084	3,052	2,159
Depreciation and amortization	49	49	95	95
Insurance [Member] | Reportable Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	86	90	163	160
Noninterest income	9,404	8,303	18,020	16,401
Noninterest expense	7,015	6,596	13,944	13,193
Income before income taxes	2,475	1,797	4,239	3,368
Income taxes	967	670	1,629	1,259
Net Income	1,508	1,127	2,610	2,109
Selected Financial Information [Abstract]
Average assets	72,316	70,515	62,053	66,707
Depreciation and amortization	$ 228	$ 233	$ 387	$ 468