Income Taxes (Details) - USD ($) $ in Millions		12 Months Ended
		Aug. 31, 2016	Aug. 31, 2015	Aug. 31, 2014
Schedule of Income before Income Tax, Domestic and Foreign [Abstract]
U.S.		$ 2,577	$ 2,725	$ 3,386
Non - U.S.		2,567	2,586	171
Earnings Before Income Tax Provision		5,144	5,311	3,557
Current provision [Abstract]
Federal		999	846	1,207
State		56	121	109
Non - U.S.		371	128	35
Total current provisions for income taxes		1,426	1,095	1,351
Deferred provision [Abstract]
Federal		(183)	(23)	183
State		6	(16)	(3)
Non - U.S. - Tax Law Change		(182)	0	0
Non - U.S. - Excluding Tax Law Change		(70)	0	(5)
Total deferred provision for income taxes		(429)	(39)	175
Income tax provision		$ 997	$ 1,056	$ 1,526
Difference Between the Statutory Federal Income Tax Rate and the Effective Tax Rate [Abstract]
Federal statutory rate		35.00%	35.00%	35.00%
State income taxes, net of federal benefit		0.80%	1.30%	1.90%
Loss on Alliance Boots call option	[1]	0.00%	0.00%	8.50%
Deferred tax asset recognition	[1]	0.00%	(4.10%)	0.00%
Gain on previously held equity interest		0.00%	(5.80%)	0.00%
Foreign income taxed at non-U.S. rates		(7.80%)	(6.20%)	(3.10%)
Non-taxable income		(4.40%)	(2.60%)	0.00%
Non-deductible expenses		1.10%	2.30%	0.30%
Tax Law changes		(3.50%)	0.00%	0.00%
Tax Credits		(1.50%)	0.00%	0.00%
Other		(0.30%)	0.00%	0.30%
Effective income tax rate		19.40%	19.90%	42.90%
Remaining ownership subject to call option				55.00%
Nondeductible loss on exercise of call option		$ 0	$ 0	$ 866
Deferred tax assets [Abstract]
Postretirement benefits		190	130
Compensation and benefits		205	224
Insurance		75	68
Accrued rent		169	167
Outside basis difference		134	73
Bad debts		65	67
Tax attributes		373	341
Stock compensation		97	119
Deferred income		150	0
Other		195	93
Subtotal deferred tax assets		1,653	1,282
Less: Valuation allowance		305	125
Total deferred tax assets		1,348	1,157
Deferred tax liabilities [Abstract]
Accelerated depreciation		1,205	1,234
Inventory		388	420
Intangible assets		1,418	1,822
Equity method investment		978	333
Deferred income		0	889
Total deferred tax liabilities		3,989	4,698
Net deferred tax liabilities		2,641	3,541
Operating Loss Carryforwards [Line Items]
Income tax credits		55
Income taxes paid		1,100	1,300	1,200
Deferred tax assets operating loss carryforwards subject to expiration		139
Deferred tax assets operating loss carryforwards not subject to expiration		234
Unrecognized tax benefit reported in current income tax liabilities		51
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of year		261	193	208
Gross increases related to business combination		0	84	0
Gross increases related to tax positions in a prior period		21	45	55
Gross decreases related to tax positions in a prior period		(47)	(75)	(82)
Gross increases related to tax positions in the current period		68	63	46
Settlements with taxing authorities		(17)	(45)	(22)
Currency		(11)	0	0
Lapse of statute of limitations		(6)	(4)	(12)
Balance at end of year		269	261	193
Unrecognized tax benefits would favorably impact the effective tax rate if recognized		$ 237	227	$ 105
Number of months of increase (decrease) in unrecognized tax benefit with respect to uncertain unrecognized tax positions (in months)		12
Accrued Interest and penalties in income tax provision		$ 34	36
Interest and penalties included in income tax expense		2
Unrecorded deferred tax liability for temporary differences related to foreign subsidiaries		$ 116	$ 89
Minimum [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, expiration dates		Jan. 01, 2017
Maximum [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, expiration dates		Dec. 31, 2036
U.S. Federal [Member]
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		$ 200
State [Member]
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		226
Non-U.S. [Member]
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		$ 837

[1] Upon the amendment and immediate exercise of the call option to acquire the remaining 55% ownership of Alliance Boots, the Company was required to compare the fair value of the amended option with the book value of the original option with a gain or loss recognized for the difference. The fair value of the amended option resulted in a financial statement loss of $866 million. The loss on the Alliance Boots call option was, in part, a capital loss and available to be carried forward and offset future capital gains through fiscal 2020. In 2015, the deferred tax asset related to the loss was recognized, resulting in the 4.1% effective tax rate benefit reported in the table above.