Earnings Per Comon Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Earnings Per Share [Abstract]
Net Income	$ 5,748		$ 5,372		$ 16,630		$ 16,502
Basic, in shares	12,012	[1]	11,989	[1]	12,004	[1]	11,954	[1]
Basic Earnings, in dollars per share	$ 0.48	[1]	$ 0.45	[1]	$ 1.39	[1]	$ 1.38	[1]
Dilutive Average Shares Attributable to Stock Options, in shares	20		22		18		28
Weighted Average Shares - Diluted	12,032	[1]	12,011	[1]	12,022	[1]	11,982	[1]
Diluted Earnings, in dollars per share	$ 0.48	[1]	$ 0.45	[1]	$ 1.38	[1]	$ 1.38	[1]
Antidilutive Securities Excluded from the Calculation of Earnings Per Share, in shares	129		215		203		139

[1] Share and Per Share Amounts have been restated for the September 2012 2% stock dividend.