Business Segment Information - Schedule of Segment Information (Details) - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2021	Aug. 31, 2020
Segment Reporting Information [Line Items]
Revenue	$ 22,003	$ 19,321
Operating income (loss)	1,398	1,590
Operating Segments [Member] | FedEx Express Segment [Member]
Segment Reporting Information [Line Items]
Revenue	10,966	9,647
Operating income (loss)	567	710
Operating Segments [Member] | FedEx Ground Segment [Member]
Segment Reporting Information [Line Items]
Revenue	7,677	7,040
Operating income (loss)	671	834
Operating Segments [Member] | FedEx Freight Segment [Member]
Segment Reporting Information [Line Items]
Revenue	2,251	1,826
Operating income (loss)	390	274
Operating Segments [Member] | FedEx Services Segment [Member]
Segment Reporting Information [Line Items]
Revenue	35	8
Corporate, Other and Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	1,074	800
Operating income (loss)	$ (230)	$ (228)