Retirement Plans (Details 8) - USD ($) $ in Millions		May. 31, 2015	May. 31, 2014
Defined Benefit Plan Pension Plans With Accumulated Benefit Obligations In Excess Of Plan Assets [Abstract]
ABO	[1]	$ (26,413)	$ (23,447)
Fair value of plan assets		23,099	21,542
PBO		(27,132)	(24,218)
Net funded status		(4,033)	(2,676)
Defined Benefit Plan Plans With Benefit Obligations In Excess Of Plan Assets [Abstract]
Fair value of plan assets		23,099	21,543
PBO		(27,132)	(24,219)
Net funded status		$ (4,033)	$ (2,676)

[1] ABO not used in determination of funded status.