Commitments - Schedule of Aircraft Purchase Commitments (Details)	3 Months Ended
	Aug. 31, 2017 air-craft
Schedule of Aircraft Commitments [Line Items]
2018 (remainder)	15
2019	17
2020	19
2021	13
2022	14
Thereafter	6
Total	84
Boeing 767 Freighter [Member]
Schedule of Aircraft Commitments [Line Items]
2018 (remainder)	11
2019	15
2020	16
2021	10
2022	10
Thereafter	6
Total	68
Boeing 777 Freighter [Member]
Schedule of Aircraft Commitments [Line Items]
2018 (remainder)	4
2019	2
2020	3
2021	3
2022	4
Total	16