General - Schedule of Revenue by Service Type (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Feb. 28, 2022	Feb. 28, 2021	Feb. 28, 2022	Feb. 28, 2021
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		$ 23,641	$ 21,510	$ 69,118	$ 61,394
Operating Segments [Member] | FedEx Express Segment [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		11,304	10,788	33,875	30,803
Operating Segments [Member] | FedEx Express Segment [Member] | U.S. overnight box [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		2,275	2,078	6,694	5,951
Operating Segments [Member] | FedEx Express Segment [Member] | U.S. overnight envelope [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		479	444	1,435	1,305
Operating Segments [Member] | FedEx Express Segment [Member] | U.S. deferred [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		1,422	1,418	3,960	3,718
Operating Segments [Member] | FedEx Express Segment [Member] | Total U.S. domestic package revenue [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		4,176	3,940	12,089	10,974
Operating Segments [Member] | FedEx Express Segment [Member] | International priority [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		2,991	2,596	8,937	7,423
Operating Segments [Member] | FedEx Express Segment [Member] | International economy [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		697	653	2,072	1,927
Operating Segments [Member] | FedEx Express Segment [Member] | Total international export package revenue [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		3,688	3,249	11,009	9,350
Operating Segments [Member] | FedEx Express Segment [Member] | International domestic [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues	[1]	1,016	1,162	3,277	3,456
Operating Segments [Member] | FedEx Express Segment [Member] | Total package revenue [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		8,880	8,351	26,375	23,780
Operating Segments [Member] | FedEx Express Segment [Member] | U.S. freight [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		712	860	2,262	2,492
Operating Segments [Member] | FedEx Express Segment [Member] | International priority freight [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		948	775	2,815	2,165
Operating Segments [Member] | FedEx Express Segment [Member] | International Economy Freight [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		378	383	1,230	1,162
Operating Segments [Member] | FedEx Express Segment [Member] | International Airfreight [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		40	56	134	196
Operating Segments [Member] | FedEx Express Segment [Member] | Total freight revenue [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		2,078	2,074	6,441	6,015
Operating Segments [Member] | FedEx Express Segment [Member] | Other [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		346	363	1,059	1,008
Operating Segments [Member] | FedEx Ground Segment [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		8,800	7,980	24,741	22,364
Operating Segments [Member] | FedEx Freight Segment [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		2,253	1,836	6,776	5,598
Operating Segments [Member] | FedEx Services Segment [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		65	8	177	24
Other and eliminations [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues	[2]	$ 1,219	$ 898	$ 3,549	$ 2,605

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

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