Equity Method Investments (Details) - USD ($) $ in Millions		3 Months Ended			6 Months Ended
		Feb. 29, 2016	Feb. 28, 2015		Feb. 29, 2016	Feb. 28, 2015		Aug. 31, 2015	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Non-controlling interests		$ 170			$ 170			$ 163
Equity earnings	[1]	$ 9	$ 109	[2]	$ 20	$ 323	[2]
Alliance Boots [Member]
Schedule of Equity Method Investments [Line Items]
Equity earnings			101			315
Equity method investment ownership interest percentage		45.00%			45.00%				45.00%
Other Equity Method Investments [Member]
Schedule of Equity Method Investments [Line Items]
Equity earnings		$ 9	$ 8		$ 20	$ 8

[1] Statement of earnings information of foreign equity method investments are translated at their respective average exchange rates.

[2] Includes equity method investment in Alliance Boots from Walgreen Co.'s pre-merger 45 percent interest for one month (December 2014) and four months (September through December 2014), respectively. See Note 1, Organization.