Financing Arrangements	3 Months Ended
Aug. 31, 2015
Financing Arrangements [Abstract]
Financing Arrangements	(3) Financing Arrangements In September 2015, we expect to file a new shelf registration statement with the SEC that will allow 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 March 2018. 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 70%. Our leverage ratio of adjusted debt to capital was 61% at August 31, 2015. 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, 2015, 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 $7.2 billion at August 31, 2015 and May 31, 2015, compared with estimated fair values of $7.2 billion at August 31, 2015 and $7.4 billion at May 31, 2015. The estimated fair values were determined based on quoted market prices and the current rates offered for debt with similar terms and maturities. The fair value of our long-term debt is classified as Level 2 within the fair value hierarchy. This classification is defined as a fair value determined using market-based inputs other than quoted prices that are observable for the liability, either directly or indirectly.

Financing Arrangements

3 Months Ended

Aug. 31, 2015

(3) Financing Arrangements

In September 2015, we expect to file a new shelf registration statement with the SEC that will allow 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 March 2018. 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 70%. Our leverage ratio of adjusted debt to capital was 61% at August 31, 2015. 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, 2015, 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 $7.2 billion at August 31, 2015 and May 31, 2015, compared with estimated fair values of $7.2 billion at August 31, 2015 and $7.4 billion at May 31, 2015. The estimated fair values were determined based on quoted market prices and the current rates offered for debt with similar terms and maturities. The fair value of our long-term debt is classified as Level 2 within the fair value hierarchy. This classification is defined as a fair value determined using market-based inputs other than quoted prices that are observable for the liability, either directly or indirectly.