Retirement Benefits (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Feb. 28, 2017	Feb. 29, 2016	Feb. 28, 2017	Feb. 29, 2016
Components of net periodic benefit costs [Abstract]
Employer cash contributions to defined benefit pension plans			$ 9
Employee expected additional contribution in current fiscal year			54
Walgreen Profit Sharing Retirement Trust
Defined Contribution Plan Disclosure [Line Items]
Profit sharing provision expense	$ 49	$ 53	106	$ 111
Alliance Boots Retirement Savings Plan
Defined Contribution Plan Disclosure [Line Items]
Cost recognized in the consolidated condensed statements of earnings	28	34	56	69
Boots and Other Pension Plans
Components of net periodic benefit costs [Abstract]
Service costs	0	0	2	2
Interest costs	43	77	86	159
Expected returns on plan assets	(36)	(62)	(73)	(127)
Curtailments	2	0	2	0
Total net periodic pension costs	$ 9	$ 15	$ 17	$ 34