Business Segments and Disaggregated Revenue - Schedule of Geographical Information (Details) - USD ($) $ in Millions		3 Months Ended																12 Months Ended
		May 31, 2019		Feb. 28, 2019	[1]	Nov. 30, 2018	[1]	Aug. 31, 2018	[1]	May 31, 2018		Feb. 28, 2018	[2]	Nov. 30, 2017	[2]	Aug. 31, 2017	[2]	May 31, 2019		May 31, 2018	[4]	May 31, 2017	[4]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues		$ 17,807	[1]	$ 17,010		$ 17,824		$ 17,052		$ 17,314	[2]	$ 16,526		$ 16,313		$ 15,297		$ 69,693	[3]	$ 65,450	[3]	$ 60,319	[3]
Assets Noncurrent	[3]	41,317								38,989	[4]							41,317		38,989		35,924
U.S. [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[3]																	47,584		43,581		40,269
Assets Noncurrent	[3]	33,189								30,362	[4]							33,189		30,362		28,141
International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[3]																	22,109		21,869		20,050
Assets Noncurrent	[3]	$ 8,128								$ 8,627	[4]							8,128		8,627		7,783
FedEx Express Segment [Member] | International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[3]																	20,424		20,417		18,817
FedEx Ground Segment [Member] | International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[3]																	467		407		331
FedEx Freight Segment [Member] | International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[3]																	207		181		149
FedEx Services Segment [Member] | International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[3]																	1		3		10
Other international revenue [Member] | International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[3]																	$ 1,010		$ 861		$ 743

[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.