Income Taxes - Schedule of Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions		May 31, 2020	May 31, 2019
Components Of Deferred Tax Assets And Liabilities [Abstract]
Property, equipment, leases and intangibles	[1]	$ 3,819	$ 592
Employee benefits		1,448	1,256
Self-insurance accruals		647	585
Other		579	510
Net operating loss/credit carryforwards		1,262	1,139
Valuation allowances		(450)	(590)
Deferred Tax Assets, Net		7,305	3,492
Property, equipment, leases and intangibles	[1]	8,745	4,633
Other		375	340
Deferred Tax Liabilities		$ 9,120	$ 4,973

[1] ^{Includes impact from adoption of the new lease accounting standard in 2020. See Note 7 for additional information.}