Restructuring (Details) - USD ($) $ in Millions	3 Months Ended		27 Months Ended
	Nov. 30, 2016	Nov. 30, 2015	Nov. 30, 2016
Restructuring Reserve Disclosures [Abstract]
Total restructuring costs	$ 81	$ 90
Asset Impairments [Member]
Restructuring Reserve Disclosures [Abstract]
Total restructuring costs	48	25
Real Estate Costs [Member]
Restructuring Reserve Disclosures [Abstract]
Total restructuring costs	9	52
Severance and Other Business Transition and Exit Costs [Member]
Restructuring Reserve Disclosures [Abstract]
Total restructuring costs	24	13
Retail Pharmacy USA [Member]
Restructuring Reserve Disclosures [Abstract]
Total restructuring costs	72	85
Retail Pharmacy USA [Member] | Asset Impairments [Member]
Restructuring Reserve Disclosures [Abstract]
Total restructuring costs	46	25
Retail Pharmacy USA [Member] | Real Estate Costs [Member]
Restructuring Reserve Disclosures [Abstract]
Total restructuring costs	9	52
Retail Pharmacy USA [Member] | Severance and Other Business Transition and Exit Costs [Member]
Restructuring Reserve Disclosures [Abstract]
Total restructuring costs	17	8
Retail Pharmacy International [Member]
Restructuring Reserve Disclosures [Abstract]
Total restructuring costs	6	5
Retail Pharmacy International [Member] | Asset Impairments [Member]
Restructuring Reserve Disclosures [Abstract]
Total restructuring costs	2	0
Retail Pharmacy International [Member] | Real Estate Costs [Member]
Restructuring Reserve Disclosures [Abstract]
Total restructuring costs	0	0
Retail Pharmacy International [Member] | Severance and Other Business Transition and Exit Costs [Member]
Restructuring Reserve Disclosures [Abstract]
Total restructuring costs	4	5
Pharmaceutical Wholesale [Member]
Restructuring Reserve Disclosures [Abstract]
Total restructuring costs	3	0
Pharmaceutical Wholesale [Member] | Asset Impairments [Member]
Restructuring Reserve Disclosures [Abstract]
Total restructuring costs	0	0
Pharmaceutical Wholesale [Member] | Real Estate Costs [Member]
Restructuring Reserve Disclosures [Abstract]
Total restructuring costs	0	0
Pharmaceutical Wholesale [Member] | Severance and Other Business Transition and Exit Costs [Member]
Restructuring Reserve Disclosures [Abstract]
Total restructuring costs	3	$ 0
Cost Transformation Program [Member]
Restructuring Reserve Disclosures [Abstract]
Pre-tax charges incurred during the period			$ 1,000
Restructuring Reserve [Roll Forward]
Beginning Balance	275
Costs incurred, net of expected sublease income	81
Payments	(34)
Other - non cash	(48)
Currency translation adjustments	(2)
Ending Balance	272		272
Cost Transformation Program [Member] | Asset Impairments [Member]
Restructuring Reserve Disclosures [Abstract]
Pre-tax charges incurred during the period			496
Restructuring Reserve [Roll Forward]
Beginning Balance	0
Costs incurred, net of expected sublease income	48
Payments	0
Other - non cash	(48)
Currency translation adjustments	0
Ending Balance	0		0
Cost Transformation Program [Member] | Real Estate Costs [Member]
Restructuring Reserve Disclosures [Abstract]
Pre-tax charges incurred during the period			302
Restructuring Reserve [Roll Forward]
Beginning Balance	248
Costs incurred, net of expected sublease income	9
Payments	(12)
Other - non cash	0
Currency translation adjustments	0
Ending Balance	245		245
Cost Transformation Program [Member] | Severance and Other Business Transition and Exit Costs [Member]
Restructuring Reserve Disclosures [Abstract]
Pre-tax charges incurred during the period			249
Restructuring Reserve [Roll Forward]
Beginning Balance	27
Costs incurred, net of expected sublease income	24
Payments	(22)
Other - non cash	0
Currency translation adjustments	(2)
Ending Balance	$ 27		$ 27