Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Abstract]
Net Income	$ 2,019	$ 2,197	$ 38,660	$ 30,683
Average common shares outstanding - basic	27,510	27,343	27,479	27,322
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	122	45	112	56
Average common shares outstanding - diluted	27,632	27,388	27,591	27,378
Earnings per share of common stock - basic	$ 0.07	$ 0.08	$ 1.41	$ 1.12
Earnings per share of common stock - diluted	$ 0.07	$ 0.08	$ 1.40	$ 1.12
Antidilutive shares excluded from computation of earnings per share amount	23	35	16	27