Goodwill and Other Intangible Assets - Schedule of Goodwill (Details) $ in Millions	6 Months Ended
	Feb. 28, 2017 USD ($)
Goodwill [Roll Forward]
Net book value - Beginning Period	$ 15,527
Currency translation adjustments	(313)
Net book value - Ending Period	15,214
Reportable Segments | Retail Pharmacy USA
Goodwill [Roll Forward]
Net book value - Beginning Period	9,036
Currency translation adjustments	0
Net book value - Ending Period	9,036
Reportable Segments | Retail Pharmacy International
Goodwill [Roll Forward]
Net book value - Beginning Period	3,369
Currency translation adjustments	(146)
Net book value - Ending Period	3,223
Reportable Segments | Pharmaceutical Wholesale
Goodwill [Roll Forward]
Net book value - Beginning Period	3,122
Currency translation adjustments	(167)
Net book value - Ending Period	$ 2,955