Business Segment Information - Schedule of Segment Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 28, 2022	Feb. 28, 2021	Feb. 28, 2022	Feb. 28, 2021
Segment Reporting Information [Line Items]
Revenue	$ 23,641	$ 21,510	$ 69,118	$ 61,394
Operating income (loss)	1,326	1,005	4,321	4,060
Operating Segments [Member] | FedEx Express Segment [Member]
Segment Reporting Information [Line Items]
Revenue	11,304	10,788	33,875	30,803
Operating income (loss)	520	463	2,036	2,073
Operating Segments [Member] | FedEx Ground Segment [Member]
Segment Reporting Information [Line Items]
Revenue	8,800	7,980	24,741	22,364
Operating income (loss)	641	702	1,793	2,088
Operating Segments [Member] | FedEx Freight Segment [Member]
Segment Reporting Information [Line Items]
Revenue	2,253	1,836	6,776	5,598
Operating income (loss)	337	119	1,061	645
Operating Segments [Member] | FedEx Services Segment [Member]
Segment Reporting Information [Line Items]
Revenue	65	8	177	24
Corporate, Other and Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	1,219	898	3,549	2,605
Operating income (loss)	$ (172)	$ (279)	$ (569)	$ (746)