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Share Based Compensation (Weighted average assumptions by grant year) (Details)	3 Months Ended
	Apr. 30, 2013	Apr. 30, 2012
Share-based Compensation [Abstract]
Risk-free interest rate	0.59%	0.86%
Expected dividend yield	1.46%	1.33%
Expected volatility factor	41.39%	49.65%
Expected option term (in years)	3 years 9 months	3 years 9 months

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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