Document and Entity Information - shares	6 Months Ended
	Feb. 28, 2019	Mar. 31, 2019
Document and Entity Information [Abstract]
Entity Registrant Name	Walgreens Boots Alliance, Inc.
Entity Central Index Key	0001618921
Current Fiscal Year End Date	--08-31
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding (in shares)		914,298,978
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q2
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Feb. 28, 2019