Earnings Per Share (details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share [Abstract]
Net income	$ (8,733)	$ (8,233)	$ 30,222	$ 31,532
Average common shares outstanding - basic	27,189,000	26,987,000	27,145,000	26,962,000
Additional shares for stock based compensation plans	0	0	50,000	51,000
Average common shares outstanding - diluted	27,189,000	26,987,000	27,195,000	27,013,000
Earnings per share of common stock - basic	$ (0.32)	$ (0.31)	$ 1.11	$ 1.17
Earnings per share of common stock - diluted	$ (0.32)	$ (0.31)	$ 1.11	$ 1.17
Earnings Per Share, Diluted, Other Disclosures [Abstract]
Antidilutive Shares Excluded from Net Income Per Diluted Common Share Calculation	80,000	80,000	24,000	26,000