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Share-Based Compensation Plans Weighted Average Fair Value (Details) (Stock options [Member], USD $)	3 Months Ended
	Mar. 31, 2013
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)	6 years
Risk-free interest rate	1.10%
Volatility	61.00%
Dividend yield	0.00%
Weighted average grant date fair value per option granted (in dollars per share)	$ 2.62

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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