Business Segment Information - Schedule of Segment Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Nov. 30, 2019	Nov. 30, 2018	Nov. 30, 2019	Nov. 30, 2018
Segment Reporting Information [Line Items]
Revenues	$ 17,324	$ 17,824	$ 34,372	$ 34,876
Operating income (loss)	554	1,168	1,531	2,239
Operating Segments | FedEx Express Segment [Member]
Segment Reporting Information [Line Items]
Revenues	9,084	9,604	18,029	18,826
Operating income (loss)	236	630	521	1,018
Operating Segments | FedEx Ground Segment [Member]
Segment Reporting Information [Line Items]
Revenues	5,315	5,142	10,494	9,941
Operating income (loss)	342	590	986	1,266
Operating Segments | FedEx Freight Segment [Member]
Segment Reporting Information [Line Items]
Revenues	1,844	1,918	3,749	3,877
Operating income (loss)	141	148	335	324
Operating Segments | FedEx Services Segment [Member]
Segment Reporting Information [Line Items]
Revenues	5	4	9	13
Corporate, Other and Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	1,076	1,156	2,091	2,219
Operating income (loss)	$ (165)	$ (200)	$ (311)	$ (369)