XML 46 R75.htm IDEA: XBRL DOCUMENT

Assumption Used to Estimate Fair Value of Option Granted (Detail)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Share Based Payment Award Stock Options Valuation Assumptions [Line Items]
Dividend Yield	0.00%	0.00%	0.00%
Expected Volatility	52.00%	54.00%	55.00%
Risk Free Interest Rate	2.00%	2.00%	2.00%
Expected Lives	5 years	5 years	5 years

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