General - Schedule of Revenue by Service Type (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Feb. 29, 2020	Feb. 28, 2019	Feb. 29, 2020	Feb. 28, 2019
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		$ 17,487	$ 17,010	$ 51,859	$ 51,886
Operating Segments | FedEx Express Segment [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		8,924	9,005	26,953	27,831
Operating Segments | FedEx Express Segment [Member] | U.S. overnight box [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		1,865	1,844	5,595	5,678
Operating Segments | FedEx Express Segment [Member] | U.S. overnight envelope [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		459	433	1,395	1,345
Operating Segments | FedEx Express Segment [Member] | U.S. deferred [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		1,127	1,119	3,063	3,131
Operating Segments | FedEx Express Segment [Member] | Total U.S. domestic package revenue [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		3,451	3,396	10,053	10,154
Operating Segments | FedEx Express Segment [Member] | International priority [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		1,710	1,738	5,344	5,508
Operating Segments | FedEx Express Segment [Member] | International economy [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		810	806	2,538	2,541
Operating Segments | FedEx Express Segment [Member] | Total international export package revenue [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		2,520	2,544	7,882	8,049
Operating Segments | FedEx Express Segment [Member] | International domestic [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues	[1]	1,075	1,078	3,316	3,412
Operating Segments | FedEx Express Segment [Member] | Total package revenue [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		7,046	7,018	21,251	21,615
Operating Segments | FedEx Express Segment [Member] | U.S. freight [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		739	772	2,132	2,294
Operating Segments | FedEx Express Segment [Member] | International priority freight [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		439	477	1,376	1,574
Operating Segments | FedEx Express Segment [Member] | International Economy Freight
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		499	495	1,556	1,568
Operating Segments | FedEx Express Segment [Member] | International Airfreight [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		61	76	197	244
Operating Segments | FedEx Express Segment [Member] | Total freight revenue [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		1,738	1,820	5,261	5,680
Operating Segments | FedEx Express Segment [Member] | Other [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		140	167	441	536
Operating Segments | FedEx Ground Segment [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		5,845	5,261	16,339	15,202
Operating Segments | FedEx Freight Segment [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		1,738	1,750	5,487	5,627
Operating Segments | FedEx Services Segment [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		6	4	15	17
Other and eliminations [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues	[2]	$ 974	$ 990	$ 3,065	$ 3,209

[1] International domestic revenue relates to our international intra-country operations.

[2] Includes the FedEx Logistics, Inc. (“FedEx Logistics”) and FedEx Office and Print Services, Inc. (“FedEx Office”) operating segments.