Business Segment Information - Schedule of Segment Information (Details) - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2020	Aug. 31, 2019
Segment Reporting Information [Line Items]
Revenue	$ 19,321	$ 17,048
Operating income (loss)	1,590	977
Operating Segments [Member] | FedEx Express Segment [Member]
Segment Reporting Information [Line Items]
Revenue	9,647	8,945
Operating income (loss)	710	285
Operating Segments [Member] | FedEx Ground Segment [Member]
Segment Reporting Information [Line Items]
Revenue	7,040	5,179
Operating income (loss)	834	644
Operating Segments [Member] | FedEx Freight Segment [Member]
Segment Reporting Information [Line Items]
Revenue	1,826	1,905
Operating income (loss)	274	194
Operating Segments [Member] | FedEx Services Segment [Member]
Segment Reporting Information [Line Items]
Revenue	8	4
Corporate, Other and Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	800	1,015
Operating income (loss)	$ (228)	$ (146)