Business Segment Information - Schedule of Segment Information (Parenthetical) (Details) - USD ($) $ in Millions	3 Months Ended							12 Months Ended
	May 31, 2017	Feb. 28, 2017	Nov. 30, 2016	Aug. 31, 2016	May 31, 2016	Feb. 29, 2016	Nov. 30, 2015	May 31, 2017	May 31, 2016	May 31, 2015
Segment Reporting Information [Line Items]
TNT express integration expenses and restructuring charges	$ 124	$ 78	$ 58	$ 68				$ 327
Charges for legal reserves related to U.S. CBP pending protection matters	39							39
Ground independent contractor litigation expense	22				$ 11			22
U.S. CBP notice of action settlement						$ 69			$ 69
Ground independent contractor litigation provision						$ 204	$ 41		256	$ 197
Asset impairment charges										276
TNT acquisition [Member]
Segment Reporting Information [Line Items]
Increase in intangible asset amortization	$ 20	$ 16	$ 10	$ 28				74
Transaction and integration planning expenses									113
Eliminations, corporate and other [Member]
Segment Reporting Information [Line Items]
Mark to market pension accounting								$ (24)	$ 1,500	$ 2,200