Commitments - Additional Information (Details) $ in Billions		12 Months Ended
Jun. 18, 2018 air-craft	May 31, 2018 USD ($) air-craft
Other Aircraft Commitments Disclosure [Abstract]
Boeing 767F Conditional Aircraft Commitments		4
Boeing 777F Conditional Aircraft Commitments		3
Deposit and Progress Payments \| $		$ 1.2
Cessna SkyCourier 408 [Member]
Other Aircraft Commitments Disclosure [Abstract]
Number of aircraft agreed to purchase		50
Additional maximum number of aircraft, options to purchase		50
Aircraft expected to be delivered, earliest fiscal year		2021
Aircraft expected to be delivered, latest fiscal year		2024
ATR 72-600F [Member]
Other Aircraft Commitments Disclosure [Abstract]
Number of aircraft agreed to purchase		30
Additional maximum number of aircraft, options to purchase		20
Aircraft expected to be delivered, earliest fiscal year		2021
Aircraft expected to be delivered, latest fiscal year		2026
B777F Aircraft from 2021 to 2020 [Member]
Other Aircraft Commitments Disclosure [Abstract]
Aircraft expected to be delivered, earliest fiscal year		2020
Aircraft expected to be delivered, latest fiscal year		2021
Accelerate Delivery of Boeing 777F Conditional Aircraft Commitments		2
B777F Aircraft from 2021 to 2019 [Member]
Other Aircraft Commitments Disclosure [Abstract]
Aircraft expected to be delivered, earliest fiscal year		2019
Aircraft expected to be delivered, latest fiscal year		2021
Accelerate Delivery of Boeing 777F Conditional Aircraft Commitments		1
B777F Aircraft from 2022 to 2020 [Member]
Other Aircraft Commitments Disclosure [Abstract]
Aircraft expected to be delivered, earliest fiscal year		2020
Aircraft expected to be delivered, latest fiscal year		2022
Accelerate Delivery of Boeing 777F Conditional Aircraft Commitments		1
Additional B777F [Member] \| Subsequent Event [Member]
Other Aircraft Commitments Disclosure [Abstract]
Boeing 777F Conditional Aircraft Commitments	6
Number of aircraft agreed to purchase	12
Aircraft expected to be delivered, earliest fiscal year	2021
Aircraft expected to be delivered, latest fiscal year	2025
Additional B767F [Member] \| Subsequent Event [Member]
Other Aircraft Commitments Disclosure [Abstract]
Boeing 767F Conditional Aircraft Commitments	1
Number of aircraft agreed to purchase	12
Aircraft expected to be delivered, earliest fiscal year	2020
Aircraft expected to be delivered, latest fiscal year	2022
B777F Aircraft from 2020 to 2019 [Member] \| Subsequent Event [Member]
Other Aircraft Commitments Disclosure [Abstract]
Aircraft expected to be delivered, earliest fiscal year	2019
Aircraft expected to be delivered, latest fiscal year	2020
Accelerate Delivery of Boeing 777F Conditional Aircraft Commitments	1
B767F Aircraft from 2020 to 2019 [Member] \| Subsequent Event [Member]
Other Aircraft Commitments Disclosure [Abstract]
Aircraft expected to be delivered, earliest fiscal year	2019
Aircraft expected to be delivered, latest fiscal year	2020
Accelerate delivery of Boeing 767F conditional aircraft commitments	1
B777F [Member] \| Subsequent Event [Member]
Other Aircraft Commitments Disclosure [Abstract]
Additional maximum number of aircraft, options to purchase	14
Aircraft expected to be delivered, earliest fiscal year	2019
Aircraft expected to be delivered, latest fiscal year	2025
Number of aircrafts scheduled for delivery	24
Number of aircrafts delivered	1
Number of conditional aircraft commitments	6
Number of non conditional aircrafts	3
Number of aircrafts rescheduled delivery	11
Number of aircraft total options to purchase	25
Aircraft expected to be delivered, through fiscal year	2028
B767F [Member] \| Subsequent Event [Member]
Other Aircraft Commitments Disclosure [Abstract]
Additional maximum number of aircraft, options to purchase	6
Aircraft expected to be delivered, earliest fiscal year	2019
Aircraft expected to be delivered, latest fiscal year	2023
Number of aircrafts scheduled for delivery	69
Number of aircrafts delivered	2
Number of conditional aircraft commitments	5
Number of aircraft total options to purchase	50
Aircraft expected to be delivered, through fiscal year	2026