Parent Only Financial Information Parent Only Income Statement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Interest and Dividends on Investments	$ 70,738	$ 66,861	$ 64,138
Other Operating Income	1,354	1,238	1,024
Net Gains on Securities Transactions	129	110	540
Interest Expense	4,813	5,767	7,922
Salaries and Employee Benefits	33,064	30,941	31,182
Other Operating Expense	13,913	12,980	12,656
Income Tax Benefit	(10,610)	(10,174)	(9,079)
Net Income	24,662	23,360	21,795
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Dividends from Bank Subsidiaries	13,400	13,300	12,900
Interest and Dividends on Investments	118	116	116
Other Operating Income	847	578	549
Total Income	14,365	13,994	13,565
Interest Expense	619	620	640
Salaries and Employee Benefits	80	77	59
Other Operating Expense	885	754	860
Total Expense	1,584	1,451	1,559
Income Before Income Tax Benefit and Equity in Undistributed Net Income of Subsidiaries	12,781	12,543	12,006
Income Tax Benefit	(372)	(473)	(634)
Equity in Undistributed Net Income of Subsidiaries	11,509	10,344	9,155
Net Income	$ 24,662	$ 23,360	$ 21,795