Goodwill and Other Intangible Assets - Schedule of Goodwill (Details) - USD ($) $ in Millions		12 Months Ended
		May 31, 2019		May 31, 2018		May 31, 2019	May 31, 2017
Net Goodwill Detail [Abstract]
Gross Goodwill at May 31							$ 8,464
Accumulated impairment charges						$ (1,684)	(1,310)
Goodwill		$ 6,884		$ 6,973		6,884	7,154
Goodwill Roll Forward
Beginning Goodwill at May 31		6,973		7,154
Goodwill acquired		126	[1]	125	[2]
Purchase adjustments and other	[3]	(215)		68
Impairment charges	[4]			(374)
Ending Goodwill at May 31		6,884		6,973
Accumulated impairment charges						(1,684)	(1,310)
Corporate, Other and Eliminations [Member]
Net Goodwill Detail [Abstract]
Gross Goodwill at May 31							395
Accumulated impairment charges						(374)
Goodwill		51		395		46	395
Goodwill Roll Forward
Beginning Goodwill at May 31		51		395
Goodwill acquired	[2]			32
Purchase adjustments and other	[3]	(5)		(2)
Impairment charges	[4]			(374)
Ending Goodwill at May 31		46		51
Accumulated impairment charges						(374)
FedEx Express Segment [Member] | Operating Segments [Member]
Net Goodwill Detail [Abstract]
Gross Goodwill at May 31							4,953
Goodwill		5,100		4,953		5,016	4,953
Goodwill Roll Forward
Beginning Goodwill at May 31		5,100		4,953
Goodwill acquired		126	[1]	76	[2]
Purchase adjustments and other	[3]	(210)		71
Ending Goodwill at May 31		5,016		5,100
FedEx Ground Segment [Member] | Operating Segments [Member]
Net Goodwill Detail [Abstract]
Gross Goodwill at May 31							827
Goodwill		840		827		840	827
Goodwill Roll Forward
Beginning Goodwill at May 31		840		827
Goodwill acquired	[2]			14
Purchase adjustments and other	[3]			(1)
Ending Goodwill at May 31		840		840
FedEx Freight Segment [Member] | Operating Segments [Member]
Net Goodwill Detail [Abstract]
Gross Goodwill at May 31							764
Accumulated impairment charges						(133)	(133)
Goodwill		634		631		634	631
Goodwill Roll Forward
Beginning Goodwill at May 31		634		631
Goodwill acquired	[2]			3
Ending Goodwill at May 31		634		634
Accumulated impairment charges						(133)	(133)
FedEx Services Segment [Member] | Operating Segments [Member]
Net Goodwill Detail [Abstract]
Gross Goodwill at May 31							1,525
Accumulated impairment charges						(1,177)	(1,177)
Goodwill		348		348		348	348
Goodwill Roll Forward
Beginning Goodwill at May 31		348		348
Ending Goodwill at May 31		$ 348		$ 348
Accumulated impairment charges						$ (1,177)	$ (1,177)

[1] Goodwill acquired relates to the acquisitions of Flying Cargo and the controlling interest in an existing joint venture with Swiss Post. See Note 3 for more information.

[2] Goodwill acquired relates to the acquisitions of Northwest Research and P2P. See Note 3 for more information.

[3] Primarily purchase price allocation-related adjustments, currency translation adjustments and acquired goodwill related to immaterial acquisitions.

[4] Impairment charges related to the goodwill impairment of FedEx Supply Chain described below.