Shareholders' Equity and Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended		6 Months Ended
		Nov. 15, 2011	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Jan. 21, 2015
Class of Stock [Line Items]
Stock repurchased					$ 3,668	$ 0
Shareholders with certain limited exceptions (in hundredths)		5.00%
Number of Series C Junior participating preferred stock purchase by each right		1/1000
Beneficial ownership level (in hundredths)		4.99%
Discount to current market price of the common stock (in hundredths)		50.00%
Earnings Per Share Reconciliation [Abstract]
Net income			$ 5,619	$ 6,052	$ 9,400	$ 9,190
Weighted average shares outstanding (in shares)	[1]		22,889,000	22,928,000	22,943,000	22,908,000
Restricted stock units (in shares)			310,000	305,000	310,000	304,000
Effect of stock options (in shares)			120,000	126,000	120,000	126,000
Stock units for deferred compensation plan for non-employee directors (in shares)			111,000	107,000	111,000	116,000
Weighted average shares outstanding for calculation of diluted earnings per share (in shares)			23,430,000	23,466,000	23,484,000	23,454,000
Net income per common share [Abstract]
Basic (in dollars per share)	[1]		$ 0.25	$ 0.26	$ 0.41	$ 0.40
Diluted (in dollars per share)			$ 0.24	$ 0.26	$ 0.40	$ 0.39
Common Stock [Member]
Class of Stock [Line Items]
Stock repurchase program percentage of shares authorized to be repurchased (in hundredths)							5.00%
Stock repurchased (in shares)					277,415
Stock repurchased					$ 3,700
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of diluted loss per share (in shares)			30,000	30,000	30,000	30,000

[1] Basic net income per common share includes weighted average common shares outstanding during the period and participating share awards.