Parent Only Financial Information Parent Only Statement of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash Flows from Operating Activities:
Net Income	$ 26,534	$ 24,662	$ 23,360
Stock-Based Compensation Expense	287	308	360
Stock-Based Compensation Expense	287	308	360
Net Cash Provided By Operating Activities	34,695	28,926	30,641
Cash Flows from Investing Activities:
Proceeds from the Sale of Securities Available-for-Sale	97,930	66,551	49,928
Purchases of Securities Available-for-Sale	(134,950)	(201,820)	(113,953)
Net Cash Used In Investing Activities	(157,789)	(229,539)	(67,693)
Cash Flows from Financing Activities:
Shares Issued for Stock Option Exercises, net	2,404	918	1,454
Shares Issued Under the Employee Stock Purchase Plan	493	494	488
Shares Issued for Dividend Reinvestment Plans	1,743	886	0
Tax Benefit for Exercises of Stock Options	188	59	25
Purchase of Treasury Stock	(2,141)	(1,498)	(2,455)
Cash Dividends Paid	(13,092)	(12,700)	(12,407)
Net Cash Provided By Financing Activities	129,381	205,386	33,367
Net Increase (Decrease) in Cash and Cash Equivalents	6,287	4,773	(3,685)
Cash and Cash Equivalents at Beginning of Year	51,068	46,295	49,980
Cash and Cash Equivalents at End of Year	57,355	51,068	46,295
Interest on Deposits and Borrowings	5,341	4,856	5,932
Shares Issued for Acquisition of Subsidiary	0	0	91
Parent Company [Member]
Cash Flows from Operating Activities:
Net Income	26,534	24,662	23,360
Undistributed Net Income of Subsidiaries	(15,283)	(11,509)	(10,344)
Stock-Based Compensation Expense	196	227	197
Stock-Based Compensation Expense	287	308	360
Changes in Other Assets and Other Liabilities	(1,177)	(1,419)	(1,014)
Net Cash Provided By Operating Activities	10,557	12,269	12,559
Cash Flows from Investing Activities:
Proceeds from the Sale of Securities Available-for-Sale	0	47	45
Purchases of Securities Available-for-Sale	0	(47)	(45)
Net Cash Used In Investing Activities	0	0	0
Cash Flows from Financing Activities:
Shares Issued for Stock Option Exercises, net		918	1,454
Shares Issued Under the Employee Stock Purchase Plan		494	488
Shares Issued for Dividend Reinvestment Plans		886	0
Tax Benefit for Exercises of Stock Options	188	59	25
Purchase of Treasury Stock	(2,141)	(1,498)	(2,455)
Cash Dividends Paid	(13,092)	(12,700)	(12,407)
Net Cash Provided By Financing Activities	(10,405)	(11,841)	(12,895)
Net Increase (Decrease) in Cash and Cash Equivalents	152	428	(336)
Cash and Cash Equivalents at Beginning of Year	3,441	3,013	3,349
Cash and Cash Equivalents at End of Year	3,593	3,441	3,013
Interest on Deposits and Borrowings	691	619	620
Shares Issued for Acquisition of Subsidiary	$ 0	$ 0	$ 91