Financing Arrangements	6 Months Ended
Nov. 30, 2018
Debt And Capital Lease Obligations [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. During the second quarter of 2019, we issued $1.25 billion of senior unsecured debt under our current shelf registration statement, comprised of $400 million of 4.20% fixed-rate notes due in October 2028, and $850 million of 4.95% fixed-rate notes due in October 2048. Interest on these notes is paid semi-annually. We used the net proceeds to redeem the $750 million aggregate principal amount of 8.00% notes due January 15, 2019, and for general corporate purposes. We have a five-year $2.0 billion revolving credit facility that expires in November 2020. The facility, which includes a $500 million letter of credit sublimit, is available to finance our operations and other cash flow needs. The agreement contains a financial covenant, which requires us to maintain a ratio of debt to consolidated earnings (excluding non-cash retirement plans mark-to-market adjustments and non-cash asset impairment charges) before interest, taxes, depreciation and amortization (“adjusted EBITDA”) of not more than 3.5 to 1.0, calculated as of the end of the applicable quarter on a rolling four-quarters basis. The ratio of our debt to adjusted EBITDA was 2.1 to 1.0 at November 30, 2018. We believe this covenant is the 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 this financial 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. During the second quarter of 2019, we issued commercial paper to provide us with additional short-term liquidity. The maximum amount outstanding during the quarter was $600 million. Our commercial paper program is backed by unused commitments under the revolving credit facility and borrowings under the program reduce the amount available under the credit facility. As of November 30, 2018, $250 million of commercial paper and $54 million in letters of credit were outstanding, leaving $1.696 billion available under the revolving credit facility for future borrowings. Long-term debt, exclusive of capital leases, had carrying values of $16.9 billion at November 30, 2018 and $16.5 billion at May 31, 2018, compared with estimated fair values of $16.2 billion at November 30, 2018 and $16.6 billion at May 31, 2018. The annualized weighted-average interest rate on long-term debt was 3.5% at November 30, 2018. 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

6 Months Ended

Nov. 30, 2018

Debt And Capital Lease Obligations [Abstract]

(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.

During the second quarter of 2019, we issued $1.25 billion of senior unsecured debt under our current shelf registration statement, comprised of $400 million of 4.20% fixed-rate notes due in October 2028, and $850 million of 4.95% fixed-rate notes due in October 2048. Interest on these notes is paid semi-annually. We used the net proceeds to redeem the $750 million aggregate principal amount of 8.00% notes due January 15, 2019, and for general corporate purposes.

We have a five-year $2.0 billion revolving credit facility that expires in November 2020. The facility, which includes a $500 million letter of credit sublimit, is available to finance our operations and other cash flow needs. The agreement contains a financial covenant, which requires us to maintain a ratio of debt to consolidated earnings (excluding non-cash retirement plans mark-to-market adjustments and non-cash asset impairment charges) before interest, taxes, depreciation and amortization (“adjusted EBITDA”) of not more than 3.5 to 1.0, calculated as of the end of the applicable quarter on a rolling four-quarters basis. The ratio of our debt to adjusted EBITDA was 2.1 to 1.0 at November 30, 2018. We believe this covenant is the 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 this financial 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.

During the second quarter of 2019, we issued commercial paper to provide us with additional short-term liquidity. The maximum amount outstanding during the quarter was $600 million. Our commercial paper program is backed by unused commitments under the revolving credit facility and borrowings under the program reduce the amount available under the credit facility. As of November 30, 2018, $250 million of commercial paper and $54 million in letters of credit were outstanding, leaving $1.696 billion available under the revolving credit facility for future borrowings.

Long-term debt, exclusive of capital leases, had carrying values of $16.9 billion at November 30, 2018 and $16.5 billion at May 31, 2018, compared with estimated fair values of $16.2 billion at November 30, 2018 and $16.6 billion at May 31, 2018. The annualized weighted-average interest rate on long-term debt was 3.5% at November 30, 2018. 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.