Commitments - Additional Information (Details) $ in Millions	6 Months Ended
	Nov. 30, 2019 USD ($) air-craft
Other Aircraft Commitments Disclosure [Abstract]
Deposit and Progress Payments | $	$ 735
B767F [Member]
Other Aircraft Commitments Disclosure [Abstract]
Conditional Aircraft Commitments	4
Number of additional aircraft agreed to purchase options exercised	6
Aircraft expected to be delivered, fiscal year	2022
B777F [Member]
Other Aircraft Commitments Disclosure [Abstract]
Conditional Aircraft Commitments	6