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, 2017	[2],[3]	Feb. 28, 2017	[2],[3]	Nov. 30, 2016	[2],[3]	Aug. 31, 2016	[2],[3]	May 31, 2016	[3],[4]	Feb. 29, 2016	[3],[4]	Nov. 30, 2015	[3],[4]	Aug. 31, 2015	[3],[4]	May 31, 2017	May 31, 2016	May 31, 2015
Basic earnings per common share:
Net earnings allocable to common shares	[1]																	$ 2,993	$ 1,818	$ 1,048
Weighted-average common shares																		266.0	276.0	283.0
Basic earnings per common share		$ 3.81		$ 2.11		$ 2.63		$ 2.69		$ (0.26)		$ 1.86		$ 2.47		$ 2.45		$ 11.24	$ 6.59	$ 3.70
Diluted earnings per common share:
Net earnings allocable to common shares	[1]																	$ 2,993	$ 1,818	$ 1,048
Weighted-average common shares																		266.0	276.0	283.0
Dilutive effect of share-based awards																		4.0	3.0	4.0
Weighted-average diluted shares																		270.0	279.0	287.0
Diluted earnings per common share		$ 3.75		$ 2.07		$ 2.59		$ 2.65		$ (0.26)		$ 1.84		$ 2.44		$ 2.42		$ 11.07	$ 6.51	$ 3.65
Anti-dilutive options excluded from diluted earnings per common share																		4.5	3.9	2.1

[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 2017 include $124 million, $78 million, $58 million and $68 million, respectively, of TNT Express integration expenses and restructuring charges, and $20 million, $16 million, $10 million and $28 million, respectively, of increased intangible asset amortization as a result of the TNT Express acquisition. The fourth quarter of 2017 includes $39 million of charges for legal reserves related to certain pending CBP matters involving FedEx Trade Networks, $22 million of charges in connection with the settlement of and certain expected losses relating to independent contractor litigation matters at FedEx Ground and $24 million related to the retirement plans MTM gain.

[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 of 2016 includes a $1.5 billion retirement plans MTM loss and TNT Express transaction, financing and integration-planning expenses and immaterial financial results from the time of acquisition totaling $79 million. In addition, the fourth quarter of 2016 includes a $76 million favorable tax impact from an internal corporate legal entity restructuring to facilitate the integration of FedEx Express and TNT Express and $11 million of expenses related to independent contractor litigation matters at FedEx Ground. The third quarter of 2016 includes provisions related to independent contractor litigation matters at FedEx Ground for $204 million and expenses related to the settlement of a CBP notice of action in the amount of $69 million (in each case, net of recognized immaterial insurance recovery), as well as TNT Express transaction, financing and integration-planning expenses of $25 million. The second quarter of 2016 includes provisions related to independent contractor litigation matters at FedEx Ground for $41 million and $19 million of TNT Express transaction, financing and integration-planning expenses.