XML 26 R35.htm IDEA: XBRL DOCUMENT

Weighted Average Assumptions Used to Calculate Fair Value of Options Granted (Detail)	3 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Share based Compensation Arrangement by Share based Payment Award, Fair Value Assumptions, Method Used [Line Items]
Risk-free interest rate	0.78%	1.83%
Expected option life (years)	4 years 3 months 29 days	5 years 3 months 18 days
Expected volatility	56.30%	51.60%

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