Summary of Quarterly Operating Results (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended																12 Months Ended
	May 31, 2016		Feb. 29, 2016		Nov. 30, 2015		Aug. 31, 2015		May 31, 2015		Feb. 28, 2015		Nov. 30, 2014		Aug. 31, 2014		May 31, 2016	May 31, 2015	May 31, 2014
Selected Quarterly Financial Information [Abstract]
Revenues	$ 12,979	[1]	$ 12,654	[1]	$ 12,453	[1]	$ 12,279		$ 12,114	[2]	$ 11,716		$ 11,939		$ 11,684		$ 50,365	$ 47,453	$ 45,567
Operating income	(68)	[1]	864	[1]	1,137	[1]	1,144		(1,321)	[2]	1,038		1,088		1,062		3,077	1,867	3,815
Net income	$ (70)	[1]	$ 507	[1]	$ 691	[1]	$ 692		$ (895)	[2]	$ 628		$ 663		$ 653		$ 1,820	$ 1,050	$ 2,324
Basic earnings per common share	$ (0.26)	[1],[3]	$ 1.86	[1],[3]	$ 2.47	[1],[3]	$ 2.45	[3]	$ (3.16)	[2],[3]	$ 2.21	[3]	$ 2.34	[3]	$ 2.29	[3]	$ 6.59	$ 3.70	$ 7.56
Diluted earnings per common share	$ (0.26)	[1],[3]	$ 1.84	[1],[3]	$ 2.44	[1],[3]	$ 2.42	[3]	$ (3.16)	[2],[3]	$ 2.18	[3]	$ 2.31	[3]	$ 2.26	[3]	$ 6.51	$ 3.65	$ 7.48
Retirement plans mark-to-market adjustment	$ 1,500								$ 2,200								$ 1,498	$ 2,190	$ 15
Ground independent contractor litigation provision			$ 204		$ 41				197								256
Asset Impairment Charges									$ 276									$ 276
TNT transaction financing integration financial operating results	79
Internal restructuring	76																(76)
Ground independent contractor litigation expense	$ 11
U.S. CBP notice of action settlement			69														$ 69
TNT transaction financing intergration expense			$ 25		$ 19

[1] The fourth quarter of 2016 includes a $1.5 billion retirement plans mark-to-market 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 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 U.S. Customs and Border Protection notice of action in the amount of $69 million, 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.

[2] The fourth quarter of 2015 includes a $2.2 billion retirement plans mark-to-market loss, $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 at FedEx Express and a $197 million reserve increase due to the settlement of a legal matter at FedEx Ground.

[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.