Summary of Major Accounting Policies (Details) - USD ($)	12 Months Ended
	Aug. 31, 2015	Aug. 31, 2014	Aug. 31, 2013	Dec. 31, 2014	Mar. 18, 2013	Aug. 02, 2012
Equity Method Investments [Abstract]
Common shares transfer (in shares)	1,172,513,618	1,028,180,150
Cash and Cash Equivalents [Abstract]
Minimum number of days for settlement of credit and debit charges	2 days
Maximum number of days for settlement of credit and debit charges	7 days
Credit and debit card receivables	$ 165,000,000	$ 229,000,000
Outstanding checks in excess of funds on deposit at certain banks	448,000,000	267,000,000
Bank overdrafts included in short-term borrowings	45,000,000	0
Restricted Cash [Abstract]
Restricted cash	184,000,000	0
Inventory [Abstract]
Inventory increase in carrying amount if valued on LIFO basis	2,500,000,000	2,300,000,000
Property, Plant and Equipment [Line Items]
Property and equipment	22,608,000,000	19,096,000,000
Less: accumulated depreciation and amortization	7,540,000,000	6,839,000,000
Property and equipment, net	15,068,000,000	12,257,000,000
Depreciation expense for property and equipment	$ 1,300,000,000	923,000,000	$ 894,000,000
Financial Instruments [Abstract]
Minimum highly effective hedging percentage	80.00%
Maximum highly effective hedging percentage	125.00%
Impaired Assets and Liabilities for Store Closings [Abstract]
Impairment charges		167,000,000	30,000,000
Reserve for store closings	$ 446,000,000	257,000,000
Advertising Costs [Abstract]
Net advertising expenses included in selling, general and administrative expenses	$ 491,000,000	265,000,000	286,000,000
Points Earned Through Loyalty Programs [Abstract]
Number of years to recognize breakage income	3 years
Stock Compensation Plans [Abstract]
Total stock-based compensation expense	$ 109,000,000	114,000,000	104,000,000
Recognized tax benefit, stock-based compensation	7,000,000	31,000,000	30,000,000
Unrecognized compensation cost related to non-vested awards	$ 137,000,000
Compensation cost not yet recognized period for recognition	3 years
Interest Expense [Abstract]
Interest paid, net of capitalized interest	$ 472,000,000	$ 161,000,000	$ 158,000,000
Earnings Per Share [Abstract]
Outstanding options to purchase common shares excluded from earnings per share calculations (in shares)	2,500,000	3,500,000	12,300,000
New Accounting Pronouncements [Abstract]
Impact of ASU on non-current assets and long-term debt	$ 20,000,000	$ 20,000,000
Cost Transformation Restructuring Program [Member]
Impaired Assets and Liabilities for Store Closings [Abstract]
Impairment charges	386,000,000
Reserve for store closings	219,000,000
Trade Accounts Receivable [Member]
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year	173,000,000	154,000,000	$ 99,000,000
Bad debt provision	90,000,000	86,000,000	124,000,000
Write-offs	(53,000,000)	(67,000,000)	(69,000,000)
Divestitures	(37,000,000)	0	0
Currency translation	(1,000,000)	0	0
Balance at end of year	$ 172,000,000	173,000,000	154,000,000
Land and Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of assets	20 years
Property and equipment	$ 3,687,000,000	3,418,000,000
Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 7,705,000,000	6,901,000,000
Building and Building Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of assets	50 years
Building and Building Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of assets	13 years
Fixtures, Plant And Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 8,904,000,000	7,559,000,000
Fixtures, Plant And Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of assets	20 years
Fixtures, Plant And Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of assets	3 years
Capitalized System Development Costs And Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 1,491,000,000	688,000,000
Internally developed software amortization	178,000,000	127,000,000	$ 105,000,000
Unamortized capitalized software costs	$ 1,000,000,000	676,000,000
Capitalized System Development Costs And Software [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful life of capitalized software costs	8 years
Capitalized System Development Costs And Software [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful life of capitalized software costs	3 years
Capital Lease Properties [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 821,000,000	$ 530,000,000
Alliance Boots [Member]
Equity Method Investments [Abstract]
Ownership percentage		45.00%		45.00%		45.00%
Noncontrolling interest	100.00%
AmerisourceBergen Corporation [Member] | Maximum [Member]
Equity Method Investments [Abstract]
Common shares transfer (in shares)					19,859,795
Walgreens Boots Alliance Development GmbH [Member]
Equity Method Investments [Abstract]
Ownership percentage	72.50%
Ownership interest percentage prior to Second Step Transaction	50.00%
Noncontrolling interest	27.50%
Equity method ownership option to repurchase shares, amount	$ 100,000
Alliance Healthcare Italia Distribuzione S.p.A. [Member]
Equity Method Investments [Abstract]
Ownership percentage				5.00%
Common shares transfer (in shares)				320