Business Segment Information - Schedule of Segment Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Nov. 30, 2017	Nov. 30, 2016	Nov. 30, 2017	Nov. 30, 2016
Segment Reporting Information [Line Items]
Revenues	$ 16,313	$ 14,931	$ 31,610	$ 29,594
Operating Income	1,262	1,167	2,379	2,431
FedEx Express Segment [Member]
Segment Reporting Information [Line Items]
Revenues	9,354	8,642	18,006	17,102
Operating Income	717	706	1,150	1,316
FedEx Ground Segment [Member]
Segment Reporting Information [Line Items]
Revenues	4,929	4,419	9,568	8,709
Operating Income	521	465	1,147	1,075
FedEx Freight Segment [Member]
Segment Reporting Information [Line Items]
Revenues	1,762	1,597	3,514	3,255
Operating Income	118	88	294	223
FedEx Services Segment [Member]
Segment Reporting Information [Line Items]
Revenues	416	414	816	809
Eliminations, Corporate and Other [Member]
Segment Reporting Information [Line Items]
Revenues	(148)	(141)	(294)	(281)
Operating Income	$ (94)	$ (92)	$ (212)	$ (183)