Retirement Plans (Details 9) - USD ($) $ in Millions	12 Months Ended
	May. 31, 2015	May. 31, 2014
Pension Plans Contributions [Abstract]
Required U.S. pension plans contributions	$ 388	$ 645
Voluntary U.S. pension plans contributions	272	15
Company contributions	$ 660	$ 660
Required U.S. pension plans contributions in 2016	500
U.S. pension plans contributions in 2016	660