XML 29 R77.htm IDEA: XBRL DOCUMENT

Stock-Based Compensation - Fair Value of Options Granted, Determined, Using Weighted-Average Assumptions (Detail)	3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012	Sep. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	1.16%	1.16%	2.98%
Expected term (years)	7 years	7 years	7 years
Expected stock price volatility	76.42%	76.42%	46.00%
Dividend yield	0.00%	0.00%	1.41%

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