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Employee Share-Based Compensation (Details) (Assumptions For Options Granted [Member])	6 Months Ended
	Jun. 30, 2012
Assumptions For Options Granted [Member]
Volatility	33.03%
Expected dividends	0.00%
Expected term	5 years 9 months 18 days
Risk-free rate	1.10%

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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