Business Segments and Disaggregated Revenue - Schedule of Revenue by Service Type (Details) - USD ($) $ in Millions		3 Months Ended																12 Months Ended
		May 31, 2019	[1]	Feb. 28, 2019	[1]	Nov. 30, 2018	[1]	Aug. 31, 2018	[1]	May 31, 2018	[2]	Feb. 28, 2018	[2]	Nov. 30, 2017	[2]	Aug. 31, 2017	[2]	May 31, 2019		May 31, 2018	[4]	May 31, 2017	[4]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues		$ 17,807		$ 17,010		$ 17,824		$ 17,052		$ 17,314		$ 16,526		$ 16,313		$ 15,297		$ 69,693	[3]	$ 65,450	[3]	$ 60,319	[3]
Operating Segments [Member] | FedEx Express Segment [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		37,331		36,172		33,824
Operating Segments [Member] | FedEx Express Segment [Member] | U.S. overnight box [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		7,663		7,273		6,955
Operating Segments [Member] | FedEx Express Segment [Member] | U.S. overnight envelope [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		1,829		1,788		1,750
Operating Segments [Member] | FedEx Express Segment [Member] | U.S. deferred [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		4,225		3,738		3,526
Operating Segments [Member] | FedEx Express Segment [Member] | Total U.S. domestic package revenue [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		13,717		12,799		12,231
Operating Segments [Member] | FedEx Express Segment [Member] | International priority [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		7,405		7,461		7,045
Operating Segments [Member] | FedEx Express Segment [Member] | International economy [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		3,446		3,255		2,876
Operating Segments [Member] | FedEx Express Segment [Member] | Total international export package revenue [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		10,851		10,716		9,921
Operating Segments [Member] | FedEx Express Segment [Member] | International domestic [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues	[5]																	4,540		4,637		4,277
Operating Segments [Member] | FedEx Express Segment [Member] | Total package revenue [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		29,108		28,152		26,429
Operating Segments [Member] | FedEx Express Segment [Member] | U.S. freight [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		3,025		2,797		2,527
Operating Segments [Member] | FedEx Express Segment [Member] | International priority freight [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		2,070		2,105		1,836
Operating Segments [Member] | FedEx Express Segment [Member] | International Economy Freight
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		2,123		1,916		1,738
Operating Segments [Member] | FedEx Express Segment [Member] | International Airfreight [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		314		368		356
Operating Segments [Member] | FedEx Express Segment [Member] | Total freight revenue [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		7,532		7,186		6,457
Operating Segments [Member] | FedEx Express Segment [Member] | Other [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		691		834		938
Operating Segments [Member] | FedEx Ground Segment [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		20,522		18,395		16,503
Operating Segments [Member] | FedEx Freight Segment [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		7,582		6,812		6,070
Operating Segments [Member] | FedEx Services Segment [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues																		1,691		1,650		1,621
Corporate, Other and Eliminations [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Revenues	[6]																	$ 2,567		$ 2,421		$ 2,301

[1] 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.

[2] The fourth quarter, third quarter, second quarter and first quarter of 2018 include $136 million, $106 million, $122 million and $112 million, respectively, of TNT Express integration expenses (including any restructuring charges). The fourth quarter of 2018 includes goodwill and other asset impairment charges related to FedEx Supply Chain of $380 million and a net gain of $10 million related to the annual MTM retirement plans accounting adjustment. The fourth quarter and first quarter of 2018 include charges for legal reserves related to certain CBP matters involving FedEx Logistics of $1 million and $7 million, respectively.

[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 revenues relate to our intra-country operations.

[6] Includes the FedEx Logistics operating segment.