Parent Company Financial Statements (Statement of Income) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Expenses:
Interest on junior subordinated debentures	$ 964	$ 1,484	$ 1,570
Legal and professional fees	2,336us-gaap_ProfessionalFees	2,330us-gaap_ProfessionalFees	2,240us-gaap_ProfessionalFees
Income before income taxes	59,823	52,680	50,872
Income tax benefit	(18,999)us-gaap_IncomeTaxExpenseBenefit	(16,527)us-gaap_IncomeTaxExpenseBenefit	(15,798)us-gaap_IncomeTaxExpenseBenefit
Net income	40,824us-gaap_NetIncomeLoss	36,153us-gaap_NetIncomeLoss	35,074us-gaap_NetIncomeLoss
Parent Company [Member]
Income:
Dividends from subsidiaries	20,116	24,481	16,188
Other income	13	20	3
Total income	20,129	24,501	16,191
Expenses:
Interest on junior subordinated debentures	964	1,484	1,570
Legal and professional fees	96	145	127
Other	253	279	279
Total expenses	1,313	1,908	1,976
Income before income taxes	18,816	22,593	14,215
Income tax benefit	454	661	682
Income before equity in undistributed earnings of subsidiaries	19,270	23,254	14,897
Equity in undistributed earnings of subsidiaries	21,554	12,899	20,177
Net income	$ 40,824	$ 36,153	$ 35,074

Total costs of sales and operating expenses for the period.

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Amount of operating dividend income on securities.

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Income (Loss) from Continuing Operations before Equity in Undistributed Subsidiaries

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