Commitments - Additional Information (Details) $ in Millions	12 Months Ended
May 31, 2017 USD ($) air-craft
Other Aircraft Commitments Disclosure [Abstract]
Boeing 767F Conditional Aircraft Commitments	4
Boeing 777F Conditional Aircraft Commitments	6
Accelerate Delivery of Boeing 767F Conditional Aircraft Commitments	2
Accelerate Delivery of Boeing 777F Conditional Aircraft Commitments	2
Deposit and Progress Payments \| $	$ 729

Conditional aircraft commitments accelerate delivery of Boeing 767.

No definition available.

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Conditional aircraft commitments accelerate delivery of Boeing 777.

No definition available.

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The number of Boeing 767F aircraft committed to be purchased which are conditional on certain events.

No definition available.

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The number of Boeing 777F aircraft committed to be purchased which are conditional on certain events.

No definition available.

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Balance of deposits and progress payments on aircraft purchases and other planned aircraft-related transactions.

No definition available.

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Other aircraft commitments disclosure.

No definition available.

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