Summary of Quarterly Operating Results (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended																12 Months Ended
	May 31, 2017		Feb. 28, 2017		Nov. 30, 2016		Aug. 31, 2016		May 31, 2016		Feb. 29, 2016		Nov. 30, 2015		Aug. 31, 2015	[2]	May 31, 2017		May 31, 2016		May 31, 2015
Selected Quarterly Financial Information [Line Items]
Revenues	$ 15,728	[1]	$ 14,997	[1]	$ 14,931	[1]	$ 14,663	[1]	$ 12,979	[2]	$ 12,654	[2]	$ 12,453	[2]	$ 12,279		$ 60,319		$ 50,365		$ 47,453
Operating income	1,581	[1]	1,025	[1]	1,167	[1]	1,264	[1]	(68)	[2]	864	[2]	1,137	[2]	1,144		5,037	[3]	3,077	[4]	1,867	[5]
Net income	$ 1,020	[1]	$ 562	[1]	$ 700	[1]	$ 715	[1]	$ (70)	[2]	$ 507	[2]	$ 691	[2]	$ 692		$ 2,997		$ 1,820		$ 1,050
Basic earnings per common share	$ 3.81	[1],[6]	$ 2.11	[1],[6]	$ 2.63	[1],[6]	$ 2.69	[1],[6]	$ (0.26)	[2],[6]	$ 1.86	[2],[6]	$ 2.47	[2],[6]	$ 2.45	[6]	$ 11.24		$ 6.59		$ 3.70
Diluted earnings per common share	$ 3.75	[1],[6]	$ 2.07	[1],[6]	$ 2.59	[1],[6]	$ 2.65	[1],[6]	$ (0.26)	[2],[6]	$ 1.84	[2],[6]	$ 2.44	[2],[6]	$ 2.42	[6]	$ 11.07		$ 6.51		$ 3.65
Charges for legal reserves related to U.S. CBP pending protection matters	$ 39																$ 39
Ground independent contractor litigation expense	22								$ 11								22
Retirement plans mark-to-market adjustment	(24)								1,500								(24)		$ 1,498		$ 2,190
TNT integration expenses and restructuring charges	124		$ 78		$ 58		$ 68										327
Ground independent contractor litigation provision											$ 204		$ 41						256		$ 197
TNT transaction financing integration financial operating results									79
Internal restructuring									$ 76										76
U.S. CBP notice of action settlement											69								$ 69
TNT transaction financing integration expense											$ 25		$ 19
TNT acquisition [Member]
Selected Quarterly Financial Information [Line Items]
Increase in intangible asset amortization	$ 20		$ 16		$ 10		$ 28										$ 74

[1] 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.

[2] 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.

[3] Includes TNT Express integration expenses and restructuring charges of $327 million, increased intangible asset amortization of $74 million as a result of the TNT Express acquisition, and a gain of $24 million associated with our mark-to-market pension accounting. These expenses are included in “Eliminations, corporate and other,” the FedEx Express segment and the TNT Express segment. Also includes $39 million of charges for legal reserves related to certain pending U.S. Customs and Border Protection (“CBP”) matters involving FedEx Trade Networks and $22 million of charges in connection with the settlement of and certain expected losses relating to independent contractor litigation matters at FedEx Ground. See Note 18 below for additional information.

[4] Includes a $1.5 billion loss associated with our mark-to-market pension accounting. Also includes provisions for the settlement of and expected losses related to independent contractor litigation matters at FedEx Ground for $256 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, and transaction and integration-planning expenses related to our TNT Express acquisition of $113 million.

[5] Includes a $2.2 billion loss associated with our mark-to-market pension accounting, $276 million of impairment and related charges resulting from the decision to permanently retire and adjust the retirement schedule of certain aircraft and related engines, and a $197 million charge to increase the legal reserve associated with the settlement of a legal matter at FedEx Ground to the amount of the settlement.

[6] 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.