Retirement Benefits (Details) - USD ($) $ in Millions	3 Months Ended
	Nov. 30, 2016	Nov. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Employer cash contributions to defined benefit pension plans	$ 8
Employee expected additional contribution in current fiscal year	62
Walgreen Profit Sharing Retirement Trust [Member]
Defined Contribution Plan Disclosure [Line Items]
Profit sharing provision expense	57	$ 58
Alliance Boots Retirement Savings Plan [Member]
Defined Contribution Plan Disclosure [Line Items]
Cost recognized in the consolidated condensed statements of earnings	28	35
Boots and Other Pension Plans [Member]
Components of net periodic benefit costs [Abstract]
Service costs	2	1
Interest costs	43	81
Expected returns on plan assets	(37)	(65)
Total net periodic pension costs	$ 8	$ 17