Segment Reporting (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended	3 Months Ended	6 Months Ended
Dec. 31, 2014	Feb. 28, 2015	Feb. 28, 2014	Feb. 28, 2015 Segment	Feb. 28, 2014	Aug. 31, 2014
Segment Reporting [Abstract]
Number of reportable segments				3us-gaap_NumberOfReportableSegments
Equity interest in Alliance Boots (in hundredths)		45.00%		45.00%
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		$ 26,573us-gaap_Revenues	$ 19,605us-gaap_Revenues	$ 46,127us-gaap_Revenues	$ 37,934us-gaap_Revenues
Cost of sales		19,691us-gaap_CostOfGoodsAndServicesSold	13,955us-gaap_CostOfGoodsAndServicesSold	33,949us-gaap_CostOfGoodsAndServicesSold	27,132us-gaap_CostOfGoodsAndServicesSold
Gross Profit		6,882us-gaap_GrossProfit	5,650us-gaap_GrossProfit	12,178us-gaap_GrossProfit	10,802us-gaap_GrossProfit
Selling, general and administrative expenses		5,606	4,569	10,062	8,948
Equity earnings in Alliance Boots		101wxz_IncomeFromEquityMethodInvestments	136wxz_IncomeFromEquityMethodInvestments	315wxz_IncomeFromEquityMethodInvestments	330wxz_IncomeFromEquityMethodInvestments
Operating Income (loss)		1,377us-gaap_OperatingIncomeLoss	1,217us-gaap_OperatingIncomeLoss	2,431us-gaap_OperatingIncomeLoss	2,184us-gaap_OperatingIncomeLoss
Total assets		71,357us-gaap_Assets		71,357us-gaap_Assets		37,270us-gaap_Assets
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract]
Operating Income		1,377us-gaap_OperatingIncomeLoss	1,217us-gaap_OperatingIncomeLoss	2,431us-gaap_OperatingIncomeLoss	2,184us-gaap_OperatingIncomeLoss
Gain on previously held equity interest	706	706	0	706	0
Other (expense) income		504us-gaap_OtherNoncashIncomeExpense	(59)us-gaap_OtherNoncashIncomeExpense	703us-gaap_OtherNoncashIncomeExpense	166us-gaap_OtherNoncashIncomeExpense
Earnings (loss) before Interest and Tax Provision		2,587	1,158	3,840	2,350
Retail Pharmacy USA [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		21,048	19,605	40,602	37,934
Retail Pharmacy International [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		2,047	0	2,047	0
Pharmaceutical Wholesale [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		3,865	0	3,865	0
Eliminations and Unallocated Items [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		(387)	0	(387)	0
Reportable Segments [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		26,573	19,605	46,127	37,934
Cost of sales		19,691	13,995	33,949	27,132
Gross Profit		6,882	5,650	12,178	10,802
Selling, general and administrative expenses		5,606	4,569	10,062	8,948
Equity earnings in Alliance Boots		101	136	315	330
Operating Income (loss)		1,377	1,217	2,431	2,184
Total assets		71,357		71,357		37,270
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract]
Operating Income		1,377	1,217	2,431	2,184
Gain on previously held equity interest		706	0	706	0
Other (expense) income		504	(59)	703	166
Earnings (loss) before Interest and Tax Provision		2,587	1,158	3,840	2,350
Reportable Segments [Member] \| Retail Pharmacy USA [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		21,048	19,605	40,602	37,934
Cost of sales		15,302	13,955	29,560	27,132
Gross Profit		5,746	5,650	11,042	10,802
Selling, general and administrative expenses		4,555	4,569	9,011	8,948
Equity earnings in Alliance Boots		101	136	315	330
Operating Income (loss)		1,292	1,217	2,346	2,184
Total assets		77,466		77,466		44,275
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract]
Operating Income		1,292	1,217	2,346	2,184
Reportable Segments [Member] \| Retail Pharmacy International [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		2,017	0	2,017	0
Cost of sales		1,294	0	1,294	0
Gross Profit		753	0	753	0
Selling, general and administrative expenses		745	0	745	0
Equity earnings in Alliance Boots		0	0	0	0
Operating Income (loss)		8	0	8	0
Total assets		22,131		22,131		0
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract]
Operating Income		8	0	8	0
Reportable Segments [Member] \| Pharmaceutical Wholesale [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		3,508	0	3,508	0
Cost of sales		3,478	0	3,478	0
Gross Profit		387	0	387	0
Selling, general and administrative expenses		306	0	306	0
Equity earnings in Alliance Boots		0	0	0	0
Operating Income (loss)		81	0	81	0
Total assets		13,706		13,706		0
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract]
Operating Income		81	0	81	0
Reportable Segments [Member] \| Eliminations and Unallocated Items [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		0	0	0	0
Cost of sales		(383)	0	(383)	0
Gross Profit		(4)	0	(4)	0
Selling, general and administrative expenses		0	0	0	0
Equity earnings in Alliance Boots		0	0	0	0
Operating Income (loss)		(4)	0	(4)	0
Total assets		(41,946)		(41,946)		(7,005)
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract]
Operating Income		(4)	0	(4)	0
Intersegment Eliminations [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		0	0	0	0
Intersegment Eliminations [Member] \| Retail Pharmacy USA [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		0	0	0	0
Intersegment Eliminations [Member] \| Retail Pharmacy International [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		30	0	30	0
Intersegment Eliminations [Member] \| Pharmaceutical Wholesale [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		357	0	357	0
Intersegment Eliminations [Member] \| Eliminations and Unallocated Items [Member]
Segment Reporting Information, Operating Income (Loss) [Abstract]
Sales		$ (387)	$ 0	$ (387)	$ 0

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example, credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc.

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