Business Segments and Disaggregated Revenue - Schedule of Geographical Information (Details) - USD ($) $ in Millions		12 Months Ended
		May 31, 2022	May 31, 2021	May 31, 2020
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[1]	$ 93,512	$ 83,959	$ 69,217
Assets Noncurrent	[1]	65,629	62,197	57,154
U.S. [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[1]	64,941	58,792	48,404
Assets Noncurrent	[1]	53,311	49,407	45,691
International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[1]	28,571	25,167	20,813
Assets Noncurrent	[1]	12,318	12,790	11,463
FedEx Express Segment [Member] | International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[1]	25,564	23,085	19,177
FedEx Ground Segment [Member] | International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[1]	857	735	479
FedEx Freight Segment [Member] | International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[1]	235	190	192
FedEx Services Segment [Member] | International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[1]	1	1	1
Other international revenue [Member] | International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[1]	$ 1,914	$ 1,156	$ 964

[1] 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, operating lease right-of-use assets, 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.