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Summary of Significant Accounting Policies (Tables) | 6 Months Ended
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Jun. 30, 2014
Accounting Policies [Abstract] |
Awards outstanding [Table Text Block] | The following table presents the number of shares or units outstanding for each award type as of June 30, 2014 and December 31, 2013, respectively.
Award type |  | June 30, 2014 |  | December 31, 2013
Stock options |  | 979,277 |  |  | 1,160,464 |
Restricted stock units (time based) |  | 1,842,619 |  |  | 1,542,990 |
Restricted stock units (performance based) |  | 34,000 |  |  | — |
Stock appreciation rights |  | 705,736 |  |  | 721,028 |
Market stock units |  | 431,900 |  |  | 469,000 |
Market Stock Units Valuation Assumptions [Table Text Block] | The assumptions used to value the MSUs granted during the three and six months ended June 30, 2014 were as follows:
| Grant Date
| February 24, 2014 |  | February 11, 2014
Volatility | 51.13% |  | 50.74%
Risk-free interest rate | 0.66% |  | 0.67%
Expected option life in years | 2.85 |  | 2.89
Dividend yield | — |  | —

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- Definition Schedule of awards outstanding for each share-based compansation award type. + References No definition available. + Details
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- Definition Tabular disclosure of the significant assumptions used during the year to estimate the fair value of Market Stock Units which are performance-based awards that vest based upon the Company's relative shareholder return. + References No definition available. + Details
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