Summary of Significant Accounting Policies - Summary of Weighted-Average Shares Outstanding Used in the Basic and Diluted EPS Denominators (Details 4) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Weighted-average shares outstanding - Basic:
Common stock	32,449	32,117	32,142
Participating restricted stock			17
Total	32,449	32,117	32,159
Weighted-average shares outstanding - Diluted:
Common stock	33,736	32,873	32,459
Participating restricted stock			17
Total	33,736	32,873	32,476

This element represents nonvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid). Basic and dilutive earnings per share are generally disclosed for such shares using the two-class method.

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This element represents the weighted average total number of shares issued throughout the period including the first (beginning balance outstanding) and last (ending balance outstanding) day of the period before considering any reductions (for instance, shares held in treasury) to arrive at the weighted average number of shares outstanding. Weighted average relates to the portion of time within a reporting period that common shares have been issued and outstanding to the total time in that period. Such concept is used in determining the weighted average number of shares outstanding for purposes of calculating earnings per share (basic).

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