Summary of Quarterly Operating Results (Unaudited) (Parenthetical) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	May 31, 2019	Feb. 28, 2019	Nov. 30, 2018	Aug. 31, 2018	May 31, 2018	Feb. 28, 2018	Nov. 30, 2017	Aug. 31, 2017	May 31, 2019	May 31, 2018		May 31, 2017
Selected Quarterly Financial Information [Line Items]
Retirement plans mark-to-market adjustment	$ 3,900				$ (10)				$ 3,882	$ (10)		$ (24)
Business realignment costs	316	$ 4							320
Integration expenses	84	69	$ 114	$ 121	136	$ 106	$ 122	$ 112	388	477		327
Income tax benefit related to lower statutory Income tax rate on earnings	$ 200	60	150	$ 135	100	165			40
PROVISION FOR INCOME TAXES (BENEFIT)		90	60						115	(219)		1,582
Increase (Decrease) in Income Taxes			4
Goodwill and other asset impairment charges					380					380
Charges for legal reserves related to certain CBP matters					1			$ 7				39
Tax benefit from corporate structuring transactions					255					255	[1]	68	[1]
Tax benefits from foreign tax credits					$ 133	12	$ 80		8	225
Provisional benefit related to remeasurement of net U.S. deferred tax liability						(1,150)				(1,150)
U.S. Plans [Member]
Selected Quarterly Financial Information [Line Items]
Income tax benefit related to lower statutory Income tax rate on earnings										265
Additional provisional amount recognized one time benefit						204				204
Company contributions						$ 1,500			1,000	$ 2,500
Netherlands [Member]
Selected Quarterly Financial Information [Line Items]
PROVISION FOR INCOME TAXES (BENEFIT)		$ 50
FedEx Ground Segment [Member]
Selected Quarterly Financial Information [Line Items]
Settlement of a legal matter			$ 46						$ 46			$ 22

[1] The 2018 and 2017 net benefits consist of foreign deferred tax benefits of $434 million and $94 million, respectively, which were partially offset by U.S. deferred tax expenses of $179 million and $26 million, respectively.