Stock Based Compensation (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	6 Months Ended
Feb. 29, 2012	Feb. 28, 2011	Feb. 29, 2012	Feb. 28, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock based compensation expense for the period	$ 18	$ 20	$ 53	$ 46
Walgreen Co. Executive Stock Option Plan and the Walgreen Co. Stock Purchase/Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options granted in period	569,706	192,583	7,782,573	8,298,501
Fully recognized retiree eligible expense	2	0	4	5
Walgreen Co. Restricted Stock Unit Award Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options granted in period	33,427	24,387	753,620	783,344
Number of other than options granted during the period	15,100	7,684	31,645	17,077
Vesting schedule (in years) for the other than option awards			three
Walgreen Co. Performance Share Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options granted in period	44,327	19,324	773,999	806,791
Vesting schedule (in years) for the other than option awards			three
Total Walgreen Co. Restricted Stock Unit Award Program and Walgreen Co. Performance Share Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock based compensation expense for the period	$ 3	$ 10	$ 17	$ 20

The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock options, amortization of restricted stock, and adjustment for officers compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 28

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- Definition

Description of the period of time over which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, which may be expressed in a variety of ways (for example, in years, month and year).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph a

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- Definition

The number of shares issuable under a share-based award plan pertaining to grants made during the period on other than stock option plans (for example, phantom stock plan, stock appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(c)

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- Definition

The quantity of shares issuable on stock options awarded under the plan during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(d)

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- Definition

The amount of expense recognized during the period for options issued to all employees that are retiree eligible.

+ References

No definition available.

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