Income Taxes (Details 4) (USD $) In Millions, unless otherwise specified	May 31, 2014	May 31, 2013
Components Of Deferred Tax Assets [Abstract]
Property, equipment, leases and intangibles	$ 117	$ 154
Employee benefits	578	566
Self-insurance accruals	343	338
Other	200	165
Net operating loss/credit carryforwards	275	252
Valuation allowances	(194)	(161)
Deferred Tax Assets, Net	1,319	1,314
Components Of Deferred Tax Liabilities [Abstract]
Property, equipment, leases and intangibles	2,884	2,795
Employee benefits	10	10
Other	1,140	983
Deferred Tax Liabilities	$ 4,034	$ 3,788