Net Income per Share (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Net income	$ 7,314	$ 1,891	$ 21,101	$ 11,455
Less distributed and undistributed earnings allocated to participating securities	179	139	521	333
Net income allocated to common shares	$ 7,135	$ 1,752	$ 20,580	$ 11,122
Weighted average common shares outstanding (in shares)	24,766	24,770	24,741	24,797
Incremental shares from assumed conversions of common stock options (in shares)	7	4	8	5
Adjusted weighted average common shares outstanding (in shares)	24,773	24,774	24,749	24,802
Potentially dilutive securities not included in weighted average share calculation due to anti-dilutive effect (in shares)	0	0	0	0