Goodwill and Other Intangible Assets - Schedule of Goodwill (Details) - USD ($) $ in Millions		12 Months Ended
		May 31, 2021	May 31, 2020	May 31, 2019
Net Goodwill Detail [Abstract]
Gross Goodwill at May 31				$ 8,568
Accumulated impairment charges		$ (2,042)		(1,684)
Goodwill		6,992	$ 6,372	6,884
Goodwill Roll Forward
Beginning Goodwill at May 31		6,372	6,884
Impairment charges		0	(358)	0
Goodwill acquired	[1]	161
Other	[2]	459	(154)
Ending Goodwill at May 31		6,992	6,372	6,884
Accumulated impairment charges		(2,042)		(1,684)
Corporate, Other and Eliminations [Member]
Net Goodwill Detail [Abstract]
Gross Goodwill at May 31				1,945
Accumulated impairment charges		(1,909)		(1,551)
Goodwill		57	29	394
Goodwill Roll Forward
Beginning Goodwill at May 31		29	394
Impairment charges			(358)
Goodwill acquired	[1]	40
Other	[2]	(12)	(7)
Ending Goodwill at May 31		57	29	394
Accumulated impairment charges		(1,909)		(1,551)
FedEx Express Segment [Member] | Operating Segments [Member]
Net Goodwill Detail [Abstract]
Gross Goodwill at May 31				5,016
Goodwill		5,358	4,869	5,016
Goodwill Roll Forward
Beginning Goodwill at May 31		4,869	5,016
Goodwill acquired	[1]	18
Other	[2]	471	(147)
Ending Goodwill at May 31		5,358	4,869	5,016
FedEx Ground Segment [Member] | Operating Segments [Member]
Net Goodwill Detail [Abstract]
Gross Goodwill at May 31				840
Goodwill		943	840	840
Goodwill Roll Forward
Beginning Goodwill at May 31		840	840
Goodwill acquired	[1]	103
Ending Goodwill at May 31		943	840	840
FedEx Freight Segment [Member] | Operating Segments [Member]
Net Goodwill Detail [Abstract]
Gross Goodwill at May 31				767
Accumulated impairment charges		(133)		(133)
Goodwill		634	634	634
Goodwill Roll Forward
Beginning Goodwill at May 31		634	634
Ending Goodwill at May 31		634	$ 634	634
Accumulated impairment charges		$ (133)		$ (133)

[1] Goodwill acquired relates to the acquisition of ShopRunner. See Note 4 for more information.

[2] Primarily currency translation adjustments and purchase price allocation-related adjustments.