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Stock-Based Compensation (Monte Carlo Calculation Assumptions) (Details)	9 Months Ended	3 Months Ended
	Sep. 30, 2012	Sep. 30, 2013 Performance-Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility (percent)	47.70%	37.10%
Expected term (years)	5 years 10 months 25 days	3 years
Risk-free interest rate (percent)	1.43%	0.40%
Expected dividend yield (percent)	0.00%	0.00%

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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