Accumulated Other Comprehensive Income - Reclassification out of AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	May. 31, 2015	May. 31, 2014	May. 31, 2013
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Revenues	$ 30,601	$ 27,799	$ 25,313
Cost of sales	16,534	15,353	14,279
Selling and administrative expense	9,892	8,766	7,796
Other expense (income), net	58	(103)	15
Income before income taxes	4,205	3,544	3,256
Tax benefit (expense)	(932)	(851)	(805)
Gain (loss), net of tax	3,273	2,693	$ 2,451
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income into Income
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Gain (loss), net of tax	299	23
Gain (losses) on cash flow hedges | Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income into Income
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	261	36
Tax benefit (expense)	(2)	(9)
Gain (loss), net of tax	259	27
Gain (losses) on cash flow hedges | Foreign exchange forwards and options | Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income into Income
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Revenues	(95)	14
Cost of sales	220	12
Selling and administrative expense	0	0
Other expense (income), net	136	10
Other | Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income into Income
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Other expense (income), net	40	(4)
Income before income taxes	40	(4)
Tax benefit (expense)	0	0
Gain (loss), net of tax	$ 40	$ (4)