XML 62 R41.htm IDEA: XBRL DOCUMENT

Share-Based Compensation - Valuation Assumptions (Details) (Stock Options [Member])	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	0.80%	2.00%
Dividend yield	0.00%	0.00%
Volatility	89.00%	87.00%
Expected life (in years)	5 years 6 months	5 years 10 months 24 days

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.

+ References+ Details