Entity Information (USD $)	6 Months Ended
	Feb. 29, 2012
Entity Registrant Name	Walgreen Co.
Entity Central Index Key	0000104207
Current Fiscal Year End Date	--08-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float	$ 39,700,000,000
Entity Common Stock, Shares Outstanding	862,750,534
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q2