Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2015	Aug. 31, 2014
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	$ (233)
Translation adjustment	(131)	$ (29)
Amortization of prior service credit and other, net of tax of $3 in 2015 and $0 in 2014	(6)	(1)
Ending balance	(370)	63
Foreign currency translation gain (loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(250)	71
Translation adjustment	(131)	(29)
Ending balance	(381)	42
Retirement plans adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	17	22
Reclassification from AOCI	(6)	(1)
Ending balance	$ 11	$ 21