Segment Information - Schedule of Segment Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net interest income	$ 407,550	$ 387,533	$ 391,765
Provision for loan losses, net	7,699	14,714	11,800
Noninterest income	184,663	173,943	173,149
Noninterest expense	430,169	407,298	401,662
Income Before Income Taxes	154,345	139,464	151,452
Income taxes	48,715	31,053	35,414
Net Income	105,630	108,411	116,038
Selected Financial Information
Total assets	13,797,953	13,352,333	12,678,896
Depreciation and amortization	38,471	36,613	37,056
General Banking [Member]
Segment Reporting Information [Line Items]
Net interest income	406,406	386,596	391,092
Provision for loan losses, net	7,699	14,714	11,800
Noninterest income	116,180	107,059	105,477
Noninterest expense	373,221	354,555	348,270
Income Before Income Taxes	141,666	124,386	136,499
Income taxes	43,960	25,303	29,761
Net Income	97,706	99,083	106,738
Selected Financial Information
Total assets	13,724,193	13,278,668	12,604,112
Depreciation and amortization	37,710	35,692	36,072
Wealth Management [Member]
Segment Reporting Information [Line Items]
Net interest income	910	726	337
Noninterest income	30,285	30,117	31,245
Noninterest expense	27,561	24,165	25,346
Income Before Income Taxes	3,634	6,678	6,236
Income taxes	1,390	2,554	2,386
Net Income	2,244	4,124	3,850
Selected Financial Information
Total assets	5,592	7,501	7,471
Depreciation and amortization	131	174	183
Insurance [Member]
Segment Reporting Information [Line Items]
Net interest income	234	211	336
Noninterest income	38,198	36,767	36,427
Noninterest expense	29,387	28,578	28,046
Income Before Income Taxes	9,045	8,400	8,717
Income taxes	3,365	3,196	3,267
Net Income	5,680	5,204	5,450
Selected Financial Information
Total assets	68,168	66,164	67,313
Depreciation and amortization	$ 630	$ 747	$ 801