Retirement Benefits (Details) $ in Millions	3 Months Ended		9 Months Ended
	May. 31, 2015 USD ($)	May. 31, 2014 USD ($)	May. 31, 2015 USD ($) PensionPlan	May. 31, 2014 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Number of defined benefit pension plans | PensionPlan			3
Employer cash contributions to defined benefit pension plans			$ 132
Employee expected additional contribution in current fiscal year			18
Walgreen Profit Sharing Retirement Trust [Member]
Defined Contribution Plan Disclosure [Line Items]
Profit sharing provision expense	$ 64	$ 74	118	$ 239
Alliance Boots Retirement Savings Plan [Member]
Defined Contribution Plan Disclosure [Line Items]
Cost recognized in the consolidated condensed statements of earnings			57
Boots and Other Pension Plans [Member]
Components of net periodic benefit costs [Abstract]
Service cost	2	0	3	0
Interest cost	79	0	132	0
Expected return on plan assets	(65)	0	(108)	0
Settlements	(2)	0	(1)	0
Total postretirement benefit cost	14	0	26	0
Postretirement Health Benefit Plan[Member]
Components of net periodic benefit costs [Abstract]
Service cost	3	2	8	6
Interest cost	5	4	13	12
Amortization of actuarial loss	4	3	14	9
Amortization of prior service cost	(6)	(6)	(18)	(17)
Total postretirement benefit cost	$ 6	$ 3	$ 17	$ 10