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Benefit Plans (Details 7)	12 Months Ended
Benefit Plans (Details 7)	Dec. 31, 2012
Weighted-average assumptions for determining fair value of options granted in 2012
Risk-free interest rate	0.84%
Expected term (years)	5 years
Expected stock volatility	64.17%
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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