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Share-Based Compensation Plans Weighted Average Fair Value (Details) (Stock options [Member], USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)	6 years 1 month 6 days	6 years	6 years 2 months 12 days	6 years
Risk-free interest rate	2.20%	1.00%	1.70%	1.00%
Volatility	60.00%	65.00%	60.00%	65.00%
Dividend yield	0.00%	0.00%	0.00%	0.00%
Weighted average grant date fair value per option granted (in dollars per share)	$ 2.44	$ 2.68	$ 2.48	$ 2.68

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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