Summary of Significant Accounting Policies, Earnings per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Earnings Per Share [Abstract]
Stock options outstanding (in shares)	661				503				661	503	435
Antidilutive shares and options excluded from computation of earnings per share (in shares)									343	352	265
Net income	$ 4,916	$ 1,361	$ 5,560	$ 4,466	$ 3,972	$ 3,002	$ 2,992	$ 3,027	$ 16,303	$ 12,993	$ 18,075
Weighted average shares outstanding (in shares)									23,877	23,781	23,730
Basic income per share (in dollars per share)									$ 0.68	$ 0.55	$ 0.76
Effect of stock options outstanding [Abstract]
Assumed exercise, at the strike price at the beginning of year (in shares)									343	231	118
Assumed repurchase of shares under treasury stock method (in shares)									(201)	(186)	(25)
Diluted weighted average shares (in shares)									24,019	23,826	23,823
Diluted income per share (in dollars per share)									$ 0.68	$ 0.55	$ 0.76