Business Segments and Disaggregated Revenue - Schedule of Segment 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		May 31, 2018
Segment Reporting Information [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],[4]	$ 65,450	[3],[4]
Depreciation and amortization																		3,615		3,353		3,095
Operating income (loss)		475	[1]	$ 411		$ 554		$ 977		1,316	[2]	$ 911		$ 1,168		$ 1,071		2,417	[5]	4,466	[6]	4,272	[7]
Segment assets	[8]	73,537								54,403								73,537		54,403		52,330
Capital expenditures																		5,868		5,490		5,663
Operating Segments [Member] | FedEx Express Segment [Member]
Segment Reporting Information [Line Items]
Revenues																		35,513		37,331	[4]	36,172	[4]
Depreciation and amortization																		1,894		1,801		1,679
Operating income (loss)																		996	[5]	2,176	[6]	2,172	[7]
Segment assets	[8]	41,252								33,247								41,252		33,247		31,753
Capital expenditures																		3,560		3,550		3,461
Operating Segments [Member] | FedEx Ground Segment [Member]
Segment Reporting Information [Line Items]
Revenues																		22,733		20,522	[4]	18,395	[4]
Depreciation and amortization																		789		728		681
Operating income (loss)																		2,014	[5]	2,663	[6]	2,556	[7]
Segment assets	[8]	24,700								17,561								24,700		17,561		15,458
Capital expenditures																		1,083		808		1,178
Operating Segments [Member] | FedEx Freight Segment [Member]
Segment Reporting Information [Line Items]
Revenues																		7,102		7,582	[4]	6,812	[4]
Depreciation and amortization																		381		332		296
Operating income (loss)																		580	[5]	615	[6]	490	[7]
Segment assets	[8]	6,434								4,736								6,434		4,736		4,251
Capital expenditures																		539		544		490
Operating Segments [Member] | FedEx Services Segment [Member]
Segment Reporting Information [Line Items]
Revenues																		22		22	[4]	28	[4]
Depreciation and amortization																		413		355		308
Segment assets	[8]	7,285								6,061								7,285		6,061		5,501
Capital expenditures																		527		440		411
Corporate, Other and Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues																		3,847		4,236		4,043
Depreciation and amortization																		138		137		131
Operating income (loss)																		(1,173)	[5]	(988)	[6]	(946)	[7]
Segment assets	[8]	$ (6,134)								$ (7,202)								(6,134)		(7,202)		(4,633)
Capital expenditures																		$ 159		$ 148		$ 123

[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.

[5] 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.

[6] 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.

[7] Includes TNT Express integration expenses (including restructuring charges) of $477 million. These expenses are included in “Corporate, other and eliminations” and the FedEx Express segment. Also includes goodwill and other asset impairment charges of $380 million included in “Corporate, other and eliminations.”

[8] Segment assets include intercompany receivables.