Business Segment Information - Schedule of Segment Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Nov. 30, 2021	Nov. 30, 2020	Nov. 30, 2021	Nov. 30, 2020
Segment Reporting Information [Line Items]
Revenue	$ 23,474	$ 20,563	$ 45,477	$ 39,884
Operating income (loss)	1,597	1,465	2,995	3,055
Operating Segments [Member] | FedEx Express Segment [Member]
Segment Reporting Information [Line Items]
Revenue	11,605	10,368	22,571	20,015
Operating income (loss)	949	900	1,516	1,610
Operating Segments [Member] | FedEx Ground Segment [Member]
Segment Reporting Information [Line Items]
Revenue	8,264	7,344	15,941	14,384
Operating income (loss)	481	552	1,152	1,386
Operating Segments [Member] | FedEx Freight Segment [Member]
Segment Reporting Information [Line Items]
Revenue	2,272	1,936	4,523	3,762
Operating income (loss)	334	252	724	526
Operating Segments [Member] | FedEx Services Segment [Member]
Segment Reporting Information [Line Items]
Revenue	77	8	112	16
Corporate, Other and Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	1,256	907	2,330	1,707
Operating income (loss)	$ (167)	$ (239)	$ (397)	$ (467)