Business Segment Information - Schedule of Segment Information (Details) - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2018	Aug. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ 17,052	$ 15,297
Operating income (loss)	1,071	971
FedEx Express Segment [Member]
Segment Reporting Information [Line Items]
Revenues	9,222	8,400
Operating income (loss)	367	320
FedEx Ground Segment [Member]
Segment Reporting Information [Line Items]
Revenues	4,799	4,245
Operating income (loss)	667	606
FedEx Freight Segment [Member]
Segment Reporting Information [Line Items]
Revenues	1,959	1,664
Operating income (loss)	176	165
FedEx Services Segment [Member]
Segment Reporting Information [Line Items]
Revenues	417	400
Corporate, Other and Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	655	588
Operating income (loss)	$ (139)	$ (120)