Business Segment Information - Schedule of Segment 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
Segment Reporting Information [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
Depreciation and amortization																		2,995		2,631		2,611
Operating income		1,581	[1]	$ 1,025		$ 1,167		$ 1,264		(68)	[2]	$ 864		$ 1,137		$ 1,144		5,037	[3]	3,077	[4]	1,867	[5]
Segment assets	[6]	48,552								45,959								48,552		45,959		36,469
Capital expenditures																		5,116		4,818		4,347
FedEx Express Segment [Member]
Segment Reporting Information [Line Items]
Revenues																		27,358		26,451		27,239
Depreciation and amortization																		1,431		1,385		1,460
Operating income																		2,678	[3]	2,519	[4]	1,584	[5]
Segment assets	[6]	24,882								21,205								24,882		21,205		20,382
Capital expenditures																		2,525		2,356		2,380
TNT Express Segment [Member]
Segment Reporting Information [Line Items]
Revenues																		7,401
Depreciation and amortization																		239
Operating income	[3]																	84
Segment assets	[6]	6,939																6,939
Capital expenditures																		205
FedEx Ground Segment [Member]
Segment Reporting Information [Line Items]
Revenues																		18,075		16,574		12,984
Depreciation and amortization																		684		608		530
Operating income																		2,292	[3]	2,276	[4]	2,172	[5]
Segment assets	[6]	14,628								13,098								14,628		13,098		11,691
Capital expenditures																		1,539		1,597		1,248
FedEx Freight Segment [Member]
Segment Reporting Information [Line Items]
Revenues																		6,443		6,200		6,191
Depreciation and amortization																		269		248		230
Operating income																		397	[3]	426	[4]	484	[5]
Segment assets	[6]	3,925								3,749								3,925		3,749		3,471
Capital expenditures																		431		433		337
FedEx Services Segment [Member]
Segment Reporting Information [Line Items]
Revenues																		1,621		1,593		1,545
Depreciation and amortization																		371		384		390
Segment assets	[6]	5,682								5,390								5,682		5,390		5,356
Capital expenditures																		416		432		381
Eliminations, corporate and other [Member]
Segment Reporting Information [Line Items]
Revenues	[7]																	(579)		(453)		(506)
Depreciation and amortization	[7]																	1		6		1
Operating income	[7]																	(414)	[3]	(2,144)	[4]	(2,373)	[5]
Segment assets	[6],[7]	$ (7,504)								$ 2,517								$ (7,504)		$ 2,517		(4,431)
Capital expenditures																						$ 1

[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] Includes TNT Express integration expenses and restructuring charges of $327 million, increased intangible asset amortization of $74 million as a result of the TNT Express acquisition, and a gain of $24 million associated with our mark-to-market pension accounting. These expenses are included in “Eliminations, corporate and other,” the FedEx Express segment and the TNT Express segment. Also includes $39 million of charges for legal reserves related to certain pending U.S. Customs and Border Protection (“CBP”) matters involving FedEx Trade Networks and $22 million of charges in connection with the settlement of and certain expected losses relating to independent contractor litigation matters at FedEx Ground. See Note 18 below for additional information.

[4] Includes a $1.5 billion loss associated with our mark-to-market pension accounting. Also includes provisions for the settlement of and expected losses related to independent contractor litigation matters at FedEx Ground for $256 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, and transaction and integration-planning expenses related to our TNT Express acquisition of $113 million.

[5] Includes a $2.2 billion loss associated with our mark-to-market pension accounting, $276 million of impairment and related charges resulting from the decision to permanently retire and adjust the retirement schedule of certain aircraft and related engines, and a $197 million charge to increase the legal reserve associated with the settlement of a legal matter at FedEx Ground to the amount of the settlement.

[6] Segment assets include intercompany receivables.

[7] Includes TNT Express’s assets and immaterial financial results for 2016 from the time of acquisition (May 25, 2016).