Computation of Earnings Per Share - Schedule of Basic and Diluted Earnings per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended																12 Months Ended
		May 31, 2019	[2],[3]	Feb. 28, 2019	[2],[3]	Nov. 30, 2018	[2],[3]	Aug. 31, 2018	[2],[3]	May 31, 2018	[3],[4]	Feb. 28, 2018	[3],[4]	Nov. 30, 2017	[3],[4]	Aug. 31, 2017	[3],[4]	May 31, 2019	May 31, 2018	May 31, 2017
Basic earnings per common share:
Net earnings allocable to common shares	[1]																	$ 539	$ 4,566	$ 2,993
Weighted-average common shares																		262.0	267.0	266.0
Basic earnings per common share		$ (7.56)		$ 2.83		$ 3.56		$ 3.15		$ 4.23		$ 7.74		$ 2.89		$ 2.22		$ 2.06	$ 17.08	$ 11.24
Diluted earnings per common share:
Net earnings allocable to common shares	[1]																	$ 539	$ 4,566	$ 2,993
Weighted-average common shares																		262.0	267.0	266.0
Dilutive effect of share-based awards																		3.0	5.0	4.0
Weighted-average diluted shares																		265.0	272.0	270.0
Diluted earnings per common share		$ (7.56)		$ 2.80		$ 3.51		$ 3.10		$ 4.15		$ 7.59		$ 2.84		$ 2.19		$ 2.03	$ 16.79	$ 11.07
Anti-dilutive options excluded from diluted earnings per common share																		5.4	2.5	4.5

[1] Net earnings available to participating securities were immaterial in all periods presented.

[2] The fourth quarter, third quarter, second quarter and first quarter of 2019 include $84 million, $69 million, $114 million and $121 million, respectively, of TNT Express integration expenses (including any restructuring charges). The fourth quarter and third quarter of 2019 include business realignment costs of $316 million and $4 million, respectively. The fourth quarter includes a net loss of $3.9 billion related to the annual MTM retirement plans accounting adjustment. The second quarter of 2019 includes costs incurred in connection with the settlement of a legal matter involving FedEx Ground of $46 million.

[3] The sum of the quarterly earnings per share may not equal annual amounts due to differences in the weighted-average number of shares outstanding during the respective periods.

[4] The fourth quarter, third quarter, second quarter and first quarter of 2018 include $136 million, $106 million, $122 million and $112 million, respectively, of TNT Express integration expenses (including any restructuring charges). The fourth quarter of 2018 includes goodwill and other asset impairment charges related to FedEx Supply Chain of $380 million and a net gain of $10 million related to the annual MTM retirement plans accounting adjustment. The fourth quarter and first quarter of 2018 include charges for legal reserves related to certain CBP matters involving FedEx Logistics of $1 million and $7 million, respectively.