Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	May. 31, 2015	May. 31, 2014	May. 31, 2013
Supplemental Cash Flow Information [Abstract]
Interest (net of capitalized interest)	$ 201	$ 131	$ 80
Income taxes	1,122	820	687
Income tax refunds received	(9)	(54)	(219)
Cash tax payments, net	$ 1,113	$ 766	$ 468