Consolidated Condensed Balance Sheets (Unaudited) (Parenthetical)	Feb. 28, 2015	May 31, 2014
Statement of Financial Position [Abstract]
Preferred stock, shares authorized (shares)	100,000us-gaap_PreferredStockSharesAuthorized	100,000us-gaap_PreferredStockSharesAuthorized
Preferred stock, shares outstanding (shares)	0us-gaap_PreferredStockSharesOutstanding	0us-gaap_PreferredStockSharesOutstanding
Common stock, shares authorized (shares)	425,000,000us-gaap_CommonStockSharesAuthorized	425,000,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued (shares)	177,886,323us-gaap_CommonStockSharesIssued	176,378,412us-gaap_CommonStockSharesIssued
Common stock, shares outstanding (shares)	114,344,969us-gaap_CommonStockSharesOutstanding	117,037,784us-gaap_CommonStockSharesOutstanding
Treasury stock, shares (shares)	63,541,354us-gaap_TreasuryStockShares	59,340,628us-gaap_TreasuryStockShares

The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-Publisher SEC

-Name Regulation S-X (SX)

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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- Definition

Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Number 210

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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

+ References

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Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

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Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

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