Business Segments and Disaggregated Revenue - Schedule of Segment 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		May 31, 2017
Segment Reporting Information [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],[4]	$ 60,319	[3],[4]
Depreciation and amortization																		3,353		3,095		2,995
Operating income (loss)		1,316	[1]	$ 911		$ 1,168		$ 1,071		1,328	[2]	$ 858		$ 1,115		$ 971		4,466	[5]	4,272	[6]	4,566	[7]
Segment assets	[8]	54,403								52,330								54,403		52,330		48,552
Capital expenditures																		5,490		5,663		5,116
Operating Segments [Member] | FedEx Express Segment [Member]
Segment Reporting Information [Line Items]
Revenues																		37,331		36,172	[4]	33,824	[4]
Depreciation and amortization																		1,801		1,679		1,662
Operating income (loss)																		2,123	[5]	2,105	[6]	2,380	[7]
Segment assets	[8]	33,247								31,753								33,247		31,753		31,307
Capital expenditures																		3,550		3,461		2,725
Operating Segments [Member] | FedEx Ground Segment [Member]
Segment Reporting Information [Line Items]
Revenues																		20,522		18,395	[4]	16,503	[4]
Depreciation and amortization																		728		681		627
Operating income (loss)																		2,640	[5]	2,529	[6]	2,243	[7]
Segment assets	[8]	17,561								15,458								17,561		15,458		12,969
Capital expenditures																		808		1,178		1,490
Operating Segments [Member] | FedEx Freight Segment [Member]
Segment Reporting Information [Line Items]
Revenues																		7,582		6,812	[4]	6,070	[4]
Depreciation and amortization																		332		296		265
Operating income (loss)																		615	[5]	490	[6]	371	[7]
Segment assets	[8]	4,736								4,251	[9]							4,736		4,251	[9]	3,740	[9]
Capital expenditures																		544		490		431
Operating Segments [Member] | FedEx Services Segment [Member]
Segment Reporting Information [Line Items]
Revenues																		1,691		1,650	[4]	1,621	[4]
Depreciation and amortization																		424		382		371
Segment assets	[8]	6,972								6,377								6,972		6,377		5,682
Capital expenditures																		528		477		416
Corporate, Other and Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues																		2,567		2,421		2,301
Depreciation and amortization																		68		57		70
Operating income (loss)																		(912)	[5]	(852)	[6]	(428)	[7]
Segment assets	[8]	$ (8,113)								$ (5,509)	[9]							(8,113)		(5,509)	[9]	(5,146)	[9]
Capital expenditures																		$ 60		$ 57		$ 54

[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.

[5] Includes TNT Express integration expenses and 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 and costs incurred in connection with the settlement of a legal matter involving FedEx Ground of $46 million.

[6] Includes TNT Express integration expenses and 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.

[7] Includes TNT Express integration expenses and restructuring charges of $327 million. These expenses are included in “Corporate, other and eliminations” and the FedEx Express segment. Also includes $39 million of charges for legal reserves related to certain U.S. Customs and Border Protection (“CBP”) matters involving FedEx Logistics and $22 million of charges in connection with the settlement of and certain expected losses relating to independent contractor litigation matters at FedEx Ground.

[8] Segment assets include intercompany receivables.

[9] Amounts revised for reclassification of eliminations.