Commitments - Additional Information (Details) $ in Millions	3 Months Ended
	Aug. 31, 2020 USD ($) air-craft
Other Aircraft Commitments Disclosure [Abstract]
Deposit and Progress Payments | $	$ 632
Lessee Disclosure [Abstract]
Additional leases not yet commenced, undiscounted future payments | $	$ 1,100
Minimum [Member]
Lessee Disclosure [Abstract]
Operating lease commencement date	2021
Maximum [Member]
Lessee Disclosure [Abstract]
Operating lease commencement date	2022
B777F [Member]
Other Aircraft Commitments Disclosure [Abstract]
Conditional Aircraft Commitments	6
B767F [Member]
Other Aircraft Commitments Disclosure [Abstract]
Number of aircrafts rescheduled delivery, 2021	18
Number of aircrafts rescheduled delivery, 2022	11
Number of aircrafts rescheduled delivery, 2023	13
Number of aircrafts rescheduled delivery, 2024	4