Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Net income (loss)	$ (6,685)	$ (8,733)	$ 23,998	$ 30,222
Average common shares outstanding - basic	27,363	27,189	27,336	27,145
Additional shares for stock based compensation plans	0	0	63	50
Average common shares outstanding - diluted	27,363	27,189	27,399	27,195
Earnings per share of common stock - basic	$ (0.24)	$ (0.32)	$ 0.88	$ 1.11
Earnings per share of common stock - diluted	$ (0.24)	$ (0.32)	$ 0.88	$ 1.11
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	91	80	19	24