Business Segments and Disaggregated Revenue - Schedule of Geographical Information (Details) - USD ($) $ in Millions		3 Months Ended																12 Months Ended
		May 31, 2020		Feb. 29, 2020	[1]	Nov. 30, 2019	[1]	Aug. 31, 2019	[1]	May 31, 2019		Feb. 28, 2019	[2]	Nov. 30, 2018	[2]	Aug. 31, 2018	[2]	May 31, 2020		May 31, 2019	[4]	May 31, 2018	[4]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues		$ 17,358	[1]	$ 17,487		$ 17,324		$ 17,048		$ 17,807	[2]	$ 17,010		$ 17,824		$ 17,052		$ 69,217	[3]	$ 69,693	[3]	$ 65,450	[3]
Assets Noncurrent	[3]	57,154								41,317	[4]							57,154		41,317		38,989
U.S. [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[3]																	48,404		47,584		43,581
Assets Noncurrent	[3]	45,691								33,189	[4]							45,691		33,189		30,362
International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[3]																	20,813		22,109		21,869
Assets Noncurrent	[3]	$ 11,463								$ 8,128	[4]							11,463		8,128		8,627
FedEx Express Segment [Member] | International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[3]																	19,177		20,424		20,417
FedEx Ground Segment [Member] | International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[3]																	479		467		407
FedEx Freight Segment [Member] | International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[3]																	192		207		181
FedEx Services Segment [Member] | International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[3]																	1		1		1
Other international revenue [Member] | International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[3]																	$ 964		$ 1,010		$ 863

[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.