Business Segments and Disaggregated Revenue - Schedule of Segment Information (Details) - USD ($) $ in Millions		12 Months Ended
		May 31, 2021		May 31, 2020		May 31, 2019
Segment Reporting Information [Line Items]
Revenues	[1]	$ 83,959		$ 69,217		$ 69,693	[2]
Depreciation and amortization		3,793		3,615		3,353
Operating income (loss)		5,857	[3]	2,417	[4]	4,466	[5]
Segment assets	[6]	82,777		73,537		54,403
Capital expenditures		5,884		5,868		5,490
Operating Segments [Member] | FedEx Express Segment [Member]
Segment Reporting Information [Line Items]
Revenues		42,078		35,513		37,331	[2]
Depreciation and amortization		1,946		1,894		1,801
Operating income (loss)		2,810	[3]	996	[4]	2,176	[5]
Segment assets	[6]	46,356		41,252		33,247
Capital expenditures		3,503		3,560		3,550
Operating Segments [Member] | FedEx Ground Segment [Member]
Segment Reporting Information [Line Items]
Revenues		30,496		22,733		20,522	[2]
Depreciation and amortization		843		789		728
Operating income (loss)		3,193	[3]	2,014	[4]	2,663	[5]
Segment assets	[6]	29,134		24,700		17,561
Capital expenditures		1,446		1,083		808
Operating Segments [Member] | FedEx Freight Segment [Member]
Segment Reporting Information [Line Items]
Revenues		7,833		7,102		7,582	[2]
Depreciation and amortization		417		381		332
Operating income (loss)		1,005	[3]	580	[4]	615	[5]
Segment assets	[6]	7,371		6,434		4,736
Capital expenditures		320		539		544
Operating Segments [Member] | FedEx Services Segment [Member]
Segment Reporting Information [Line Items]
Revenues		32		22		22	[2]
Depreciation and amortization		462		413		355
Segment assets	[6]	8,639		7,285		6,061
Capital expenditures		512		527		440
Corporate, Other and Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues		3,520		3,847		4,236
Depreciation and amortization		125		138		137
Operating income (loss)		(1,151)	[3]	(1,173)	[4]	(988)	[5]
Segment assets	[6]	(8,723)		(6,134)		(7,202)
Capital expenditures		$ 103		$ 159		$ 148

[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, 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.

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

[3] Includes TNT Express integration expenses of $210 million. These expenses are included in “Corporate, other and eliminations” and the FedEx Express segment. Also includes business realignment costs of $116 million included in the FedEx Express segment.

[4] Includes TNT Express integration expenses of $270 million. These expenses are included in “Corporate, other and eliminations” and the FedEx Express segment. Also includes noncash goodwill and other asset impairment charges of $435 million primarily related to goodwill impairment at FedEx Office and from the decision to permanently retire certain aircraft and related engines at FedEx Express.

[5] Includes TNT Express integration expenses (including restructuring charges) of $388 million. These expenses are included in “Corporate, other and eliminations” and the FedEx Express segment. Also includes business realignment costs of $320 million included in “Corporate, other and eliminations” and costs incurred in connection with the settlement of a legal matter involving FedEx Ground of $46 million.

[6] Segment assets include intercompany receivables.