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, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Apr. 26, 2016	Jan. 21, 2016
Class of Stock [Line Items]
Stock repurchased					$ 15,510	$ 3,668
Shareholders with certain limited exceptions		5.00%
Number of Series C Junior participating preferred stock purchase by each right		1/1000
Beneficial ownership level		4.99%
Discount to current market price of the common stock		50.00%
Earnings Per Share Reconciliation [Abstract]
Net income			$ 6,438	$ 5,619	$ 10,538	$ 9,400
Weighted average shares outstanding (in shares)	[1]		21,281,000	22,889,000	21,516,000	22,943,000
Stock units for deferred compensation plan for non-employee directors (in shares)			114,000	111,000	114,000	111,000
Effect of stock options (in shares)			148,000	120,000	150,000	120,000
Restricted stock units (in shares)			55,000	310,000	70,000	310,000
Performance share units (in shares)			41,000	0	37,000	0
Weighted average shares outstanding for calculation of diluted earnings per share (in shares)			21,639,000	23,430,000	21,887,000	23,484,000
Net income per common share [Abstract]
Basic (in dollars per share)	[1]		$ 0.30	$ 0.25	$ 0.49	$ 0.41
Diluted (in dollars per share)			$ 0.30	$ 0.24	$ 0.48	$ 0.40
Common Stock [Member]
Class of Stock [Line Items]
Stock repurchase program percentage of shares authorized to be repurchased								5.00%
Stock repurchased (in shares)					1,059,865
Stock repurchased					$ 15,500
Stock repurchase program, remaining shares to be repurchased (in shares)			52,703		52,703
Stock repurchase program, remaining amount to be repurchased			$ 5,000		$ 5,000
Stock repurchase program, additional authorized amount							$ 5,000
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.