Earnings Per Share and Capital Structure Computation of Basic and Diluted Earnings per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net income (loss) available to common shareholders	$ 7,308	$ (7,348)	$ 26,313	$ 7,621
Weighted average common shares outstanding - Basic	39,213	39,127	39,268	39,325
Dilutive effect of stock-based awards	280	0	248	298
Weighted average common shares outstanding - Diluted	39,493	39,127	39,516	39,623
Earnings (loss) per common share - Basic	$ 0.19	$ (0.19)	$ 0.67	$ 0.19
Earnings (loss) per common share - Diluted	$ 0.19	$ (0.19)	$ 0.67	$ 0.19

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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