Business Segments and Disaggregated Revenue - Schedule of Revenue by Service Type (Details) - USD ($) $ in Millions		3 Months Ended																12 Months Ended
		May 31, 2020	[1]	Feb. 29, 2020	[1]	Nov. 30, 2019	[1]	Aug. 31, 2019	[1]	May 31, 2019	[2]	Feb. 28, 2019	[2]	Nov. 30, 2018	[2]	Aug. 31, 2018	[2]	May 31, 2020		May 31, 2019	[4]	May 31, 2018	[4]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		$ 17,358		$ 17,487		$ 17,324		$ 17,048		$ 17,807		$ 17,010		$ 17,824		$ 17,052		$ 69,217	[3]	$ 69,693	[3]	$ 65,450	[3]
Operating Segments [Member] | FedEx Express Segment [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		35,513		37,331		36,172
Operating Segments [Member] | FedEx Express Segment [Member] | U.S. overnight box [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		7,234		7,663		7,273
Operating Segments [Member] | FedEx Express Segment [Member] | U.S. overnight envelope [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		1,776		1,829		1,788
Operating Segments [Member] | FedEx Express Segment [Member] | U.S. deferred [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		4,038		4,225		3,738
Operating Segments [Member] | FedEx Express Segment [Member] | Total U.S. domestic package revenue [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		13,048		13,717		12,799
Operating Segments [Member] | FedEx Express Segment [Member] | International priority [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		7,354		7,405		7,461
Operating Segments [Member] | FedEx Express Segment [Member] | International economy [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		3,082		3,446		3,255
Operating Segments [Member] | FedEx Express Segment [Member] | Total international export package revenue [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		10,436		10,851		10,716
Operating Segments [Member] | FedEx Express Segment [Member] | International domestic [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues	[5]																	4,179		4,540		4,637
Operating Segments [Member] | FedEx Express Segment [Member] | Total package revenue [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		27,663		29,108		28,152
Operating Segments [Member] | FedEx Express Segment [Member] | U.S. freight [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		2,998		3,025		2,797
Operating Segments [Member] | FedEx Express Segment [Member] | International priority freight [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		1,915		2,070		2,105
Operating Segments [Member] | FedEx Express Segment [Member] | International Economy Freight
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		1,930		2,123		1,916
Operating Segments [Member] | FedEx Express Segment [Member] | International Airfreight [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		270		314		368
Operating Segments [Member] | FedEx Express Segment [Member] | Total freight revenue [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		7,113		7,532		7,186
Operating Segments [Member] | FedEx Express Segment [Member] | Other [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues	[6]																	737		691		834
Operating Segments [Member] | FedEx Ground Segment [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		22,733		20,522		18,395
Operating Segments [Member] | FedEx Freight Segment [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		7,102		7,582		6,812
Operating Segments [Member] | FedEx Services Segment [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		22		22		28
Corporate, Other and Eliminations [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues	[7]																	$ 3,847		$ 4,236		$ 4,043

[1] The fourth quarter, third quarter, second quarter and first quarter of 2020 include $63 million, $72 million, $64 million and $71 million, respectively, of TNT Express integration expenses. The fourth quarter includes $369 million of goodwill and other asset impairment charges associated with the FedEx Office and FedEx Logistics operating segments and a net loss of $794 million related to the annual MTM retirement plans accounting adjustment. The second quarter of 2020 includes asset impairment charges of $66 million related to the permanent retirement of 10 Airbus A310-300 aircraft and 12 related engines at FedEx Express.

[2] The fourth quarter, third quarter, second quarter and first quarter of 2019 include $84 million, $69 million, $114 million and $121 million, respectively, of TNT Express integration expenses (including any restructuring charges). The fourth quarter and third quarter of 2019 include business realignment costs of $316 million and $4 million, respectively. The fourth quarter includes a net loss of $3.9 billion related to the annual MTM retirement plans accounting adjustment. The second quarter of 2019 includes costs incurred in connection with the settlement of a legal matter involving FedEx Ground of $46 million.

[3] International revenue includes shipments that either originate in or are destined to locations outside the United States, which could include U.S. payors. Noncurrent assets include property and equipment, goodwill and other long-term assets. Our flight equipment is registered in the U.S. and is included as U.S. assets; however, many of our aircraft operate internationally.

[4] Prior year amounts have been revised to conform to the current year presentation.

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

[6] Includes the operations of FedEx Custom Critical.

[7] Includes the FedEx Office and FedEx Logistics operating segments.