Business Segment Information - Schedule of Geographical Information (Details) - USD ($) $ in Millions		3 Months Ended																12 Months Ended
		May 31, 2017		Feb. 28, 2017	[1]	Nov. 30, 2016	[1]	Aug. 31, 2016	[1]	May 31, 2016		Feb. 29, 2016	[2]	Nov. 30, 2015	[2]	Aug. 31, 2015	[2]	May 31, 2017	May 31, 2016	May 31, 2015
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues		$ 15,728	[1]	$ 14,997		$ 14,931		$ 14,663		$ 12,979	[2]	$ 12,654		$ 12,453		$ 12,279		$ 60,319	$ 50,365	$ 47,453
Assets Noncurrent		35,924								33,970								35,924	33,970	26,134
U.S. [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues																		40,269	38,070	34,216
Assets Noncurrent		28,141								25,942								28,141	25,942	23,520
International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[3]																	20,050	12,295	13,237
Assets Noncurrent		$ 7,783								$ 8,028								7,783	8,028	2,614
FedEx Express Segment [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues																		27,358	26,451	27,239
FedEx Express Segment [Member] | International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[3]																	12,094	11,672	12,772
TNT Express Segment [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues																		7,401
TNT Express Segment [Member] | International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[3]																	7,346
FedEx Ground Segment [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues																		18,075	16,574	12,984
FedEx Ground Segment [Member] | International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[3]																	451	383	311
FedEx Freight Segment [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues																		6,443	6,200	6,191
FedEx Freight Segment [Member] | International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[3]																	149	137	142
FedEx Services Segment [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues																		1,621	1,593	1,545
FedEx Services Segment [Member] | International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[3]																	$ 10	10	$ 12
Other international revenue [Member] | International [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	[3],[4]																		$ 93

[1] The fourth quarter, third quarter, second quarter, and first quarter of 2017 include $124 million, $78 million, $58 million and $68 million, respectively, of TNT Express integration expenses and restructuring charges, and $20 million, $16 million, $10 million and $28 million, respectively, of increased intangible asset amortization as a result of the TNT Express acquisition. The fourth quarter of 2017 includes $39 million of charges for legal reserves related to certain pending CBP matters involving FedEx Trade Networks, $22 million of charges in connection with the settlement of and certain expected losses relating to independent contractor litigation matters at FedEx Ground and $24 million related to the retirement plans MTM gain.

[2] The fourth quarter of 2016 includes a $1.5 billion retirement plans MTM loss and TNT Express transaction, financing and integration-planning expenses and immaterial financial results from the time of acquisition totaling $79 million. In addition, the fourth quarter of 2016 includes a $76 million favorable tax impact from an internal corporate legal entity restructuring to facilitate the integration of FedEx Express and TNT Express and $11 million of expenses related to independent contractor litigation matters at FedEx Ground. The third quarter of 2016 includes provisions related to independent contractor litigation matters at FedEx Ground for $204 million and expenses related to the settlement of a CBP notice of action in the amount of $69 million (in each case, net of recognized immaterial insurance recovery), as well as TNT Express transaction, financing and integration-planning expenses of $25 million. The second quarter of 2016 includes provisions related to independent contractor litigation matters at FedEx Ground for $41 million and $19 million of TNT Express transaction, financing and integration-planning expenses.

[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] Includes TNT Express’s revenue for 2016 from the time of acquisition (May 25, 2016).