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Benefit Plans (Details) (Employee Stock Option [Member])	3 Months Ended
	Mar. 31, 2012
Employee Stock Option [Member]
Fair value of options granted to employees
Risk-free interest rate	0.80%
Expected life of options — years	5 years 4 months 2 days
Expected stock price volatility	57.00%
Expected dividend yield	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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