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Share-Based Compensation - Valuation Assumptions (Details)	12 Months Ended
	Dec. 31, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Dividend yield	0.00%
Expected volatility	42.00%
Risk-free interest rate	0.71%
Expected option term	6 years 6 months

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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