Retirement Plans (Details 9) (USD $) In Millions, unless otherwise specified	12 Months Ended
	May 31, 2013	May 31, 2012
Pension Plans Contributions [Abstract]
Required U.S. pension plans contributions	$ 560	$ 496
Voluntary U.S. pension plans contributions		226
Company contributions	560	722
Required U.S. pension plans contributions in 2014	$ 650