Business Segment Information - Schedule of Segment Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 29, 2020	Feb. 28, 2019	Feb. 29, 2020	Feb. 28, 2019
Segment Reporting Information [Line Items]
Revenues	$ 17,487	$ 17,010	$ 51,859	$ 51,886
Operating income (loss)	411	911	1,942	3,150
Operating Segments | FedEx Express Segment [Member]
Segment Reporting Information [Line Items]
Revenues	8,924	9,005	26,953	27,831
Operating income (loss)	137	389	658	1,407
Operating Segments | FedEx Ground Segment [Member]
Segment Reporting Information [Line Items]
Revenues	5,845	5,261	16,339	15,202
Operating income (loss)	355	586	1,341	1,852
Operating Segments | FedEx Freight Segment [Member]
Segment Reporting Information [Line Items]
Revenues	1,738	1,750	5,487	5,627
Operating income (loss)	113	97	448	421
Operating Segments | FedEx Services Segment [Member]
Segment Reporting Information [Line Items]
Revenues	6	4	15	17
Corporate, Other and Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	974	990	3,065	3,209
Operating income (loss)	$ (194)	$ (161)	$ (505)	$ (530)