Goodwill and Other Intangible Assets - Schedule of Finite-Lived Intangible Assets by Major Class (Details) - USD ($) $ in Millions	Feb. 28, 2017	Aug. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Amortizable Intangible Assets	$ 3,594	$ 4,044
Accumulated amortization	1,255	1,439
Total amortizable intangible assets, net	2,339	2,605
Indefinite lived Intangible Assets	7,311	7,697
Total intangible assets, net	9,650	10,302
Trade names and trademarks
Finite-Lived Intangible Assets [Line Items]
Indefinite lived Intangible Assets	5,323	5,604
Pharmacy licenses
Finite-Lived Intangible Assets [Line Items]
Indefinite lived Intangible Assets	1,988	2,093
Customer relationships and loyalty card holders
Finite-Lived Intangible Assets [Line Items]
Gross Amortizable Intangible Assets	1,764	1,867
Accumulated amortization	328	275
Purchased prescription files
Finite-Lived Intangible Assets [Line Items]
Gross Amortizable Intangible Assets	718	932
Accumulated amortization	415	600
Favorable lease interests and non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Amortizable Intangible Assets	542	619
Accumulated amortization	344	388
Trade names and trademarks
Finite-Lived Intangible Assets [Line Items]
Gross Amortizable Intangible Assets	509	532
Accumulated amortization	129	105
Purchasing and payer contracts
Finite-Lived Intangible Assets [Line Items]
Gross Amortizable Intangible Assets	61	94
Accumulated amortization	$ 39	$ 71