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
Mar. 31, 2015	Mar. 31, 2014
Net income (loss) available to common shareholders	$ 4,910us-gaap_NetIncomeLoss	$ (254)us-gaap_NetIncomeLoss
Weighted average common shares outstanding - Basic	38,442	39,235
Dilutive effect of stock-based awards	316	0
Weighted average common shares outstanding - Diluted	38,758	39,235
Earnings (loss) per common share - Basic	$ 0.13us-gaap_EarningsPerShareBasic	$ (0.01)us-gaap_EarningsPerShareBasic
Earnings (loss) per common share - Diluted	$ 0.13us-gaap_EarningsPerShareDiluted	$ (0.01)us-gaap_EarningsPerShareDiluted

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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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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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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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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