Segment Information - Schedule of Segment Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Net interest income	$ 391,765	$ 405,336	$ 388,487
Provision for loan losses, net	11,800	7,382	(7,382)
Noninterest income	173,149	173,142	173,859
Noninterest expense	401,662	409,005	415,731
Income Before Income Taxes	151,452	162,091	153,997
Income taxes	35,414	38,529	36,937
Net Income	116,038	123,562	117,060
Selected Financial Information
Average assets	12,270,195	12,028,030	11,530,969
Depreciation and amortization	37,056	36,072	37,153
General Banking [Member]
Segment Reporting Information [Line Items]
Net interest income	391,092	404,214	387,586
Provision for loan losses, net	11,800	7,382	(7,382)
Noninterest income	105,477	107,457	113,571
Noninterest expense	348,270	355,693	367,031
Income Before Income Taxes	136,499	148,596	141,508
Income taxes	29,761	33,726	32,499
Net Income	106,738	114,870	109,009
Selected Financial Information
Average assets	12,196,144	11,957,761	11,463,945
Depreciation and amortization	36,072	35,038	35,971
Wealth Management [Member]
Segment Reporting Information [Line Items]
Net interest income	337	851	582
Noninterest income	31,245	32,209	29,446
Noninterest expense	25,346	26,733	24,713
Income Before Income Taxes	6,236	6,327	5,315
Income taxes	2,386	2,105	1,754
Net Income	3,850	4,222	3,561
Selected Financial Information
Average assets	4,034	1,821	148
Depreciation and amortization	183	190	157
Insurance [Member]
Segment Reporting Information [Line Items]
Net interest income	336	271	319
Noninterest income	36,427	33,476	30,842
Noninterest expense	28,046	26,579	23,987
Income Before Income Taxes	8,717	7,168	7,174
Income taxes	3,267	2,698	2,684
Net Income	5,450	4,470	4,490
Selected Financial Information
Average assets	70,017	68,448	66,876
Depreciation and amortization	$ 801	$ 844	$ 1,025