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Accounting for Stock-Based Compensation (Tables) | 3 Months Ended
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Aug. 31, 2012
Accounting for Stock-Based Compensation |
Assumptions used in the Black-Scholes option pricing model to estimate the fair value of each stock option grant |
|  | Three Months Ended |
|  | August 31, |
|  | 2012 |  | 2011 |
Risk-free interest rate |  | 0.6 | % | 1.5 | %
Expected volatility of common stock |  | 51 | % | 46 | %
Dividend yield |  | 2.3 | % | 1.0 | %
Expected option term in years |  | 5.4 |  | 5.7 |

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- Definition Tabular disclosure of the significant assumptions used during the year to estimate the fair value of stock options, including, but not limited to: (a) expected term of share options and similar instruments, (b) expected volatility of the entity's shares, (c) expected dividends, (d) risk-free rate(s), and (e) discount for post-vesting restrictions. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Topic 718 -SubTopic 10 -Publisher FASB -Number -Article -Subparagraph (f)(2) -Name Accounting Standards Codification -Paragraph 2 -Section 50 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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