Financing Arrangements	3 Months Ended
Aug. 31, 2011
Financing Arrangements [Abstract]
Financing Arrangements	(3) Financing Arrangements We have a shelf registration statement filed with the SEC that allows us to sell, in one or more future offerings, any combination of our unsecured debt securities and common stock. A $1 billion revolving credit facility is available to finance our operations and other cash flow needs and to provide support for the issuance of commercial paper. The revolving credit agreement expires in April 2016. The agreement contains a financial covenant, which requires us to maintain a leverage ratio of adjusted debt (long-term debt, including the current portion of such debt, plus six times our last four fiscal quarters' rentals and landing fees) to capital (adjusted debt plus total common stockholders' investment) that does not exceed 0.7 to 1.0. Our leverage ratio of adjusted debt to capital was 0.5 at August 31, 2011. We believe the leverage ratio covenant is our only significant restrictive covenant in our revolving credit agreement. Our revolving credit agreement contains other customary covenants that do not, individually or in the aggregate, materially restrict the conduct of our business. We are in compliance with the leverage ratio covenant and all other covenants of our revolving credit agreement and do not expect the covenants to affect our operations, including our liquidity or expected funding needs. As of August 31, 2011, no commercial paper was outstanding and the entire $1 billion under the revolving credit facility was available for future borrowings. Long-term debt, exclusive of capital leases, had a carrying value of $1.5 billion compared with an estimated fair value of $1.9 billion at August 31, 2011 and May 31, 2011. The estimated fair values were determined based on quoted market prices or on the current rates offered for debt with similar terms and maturities.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

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