Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Aug. 31, 2015	Aug. 31, 2014	Aug. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 20,617	$ 19,558	$ 18,236
Other comprehensive income (loss) before reclassification adjustments	(580)	353	(247)
Amounts reclassified from accumulated OCI	305
Tax benefit (provision)	(75)	(125)	87
Net other comprehensive income (loss)	(350)	228	(160)
Ending Balance	31,300	20,617	19,558
Post-retirement Liability [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	15	63	68
Other comprehensive income (loss) before reclassification adjustments	23	(77)	(9)
Amounts reclassified from accumulated OCI	0
Tax benefit (provision)	(9)	29	4
Net other comprehensive income (loss)	14	(48)	(5)
Ending Balance	29	15	63
Unrecognized Gains on Available-for-Sale Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	107	1	0
Other comprehensive income (loss) before reclassification adjustments	247	170	1
Amounts reclassified from accumulated OCI	0
Tax benefit (provision)	(95)	(64)	0
Net other comprehensive income (loss)	152	106	1
Ending Balance	259	107	1
Unrealized Loss on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(27)	0	0
Other comprehensive income (loss) before reclassification adjustments	(14)	(43)	0
Amounts reclassified from accumulated OCI	(5)
Tax benefit (provision)	6	16	0
Net other comprehensive income (loss)	(13)	(27)
Ending Balance	(40)	(27)	0
Share of Alliance Boots OCI [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(113)	(95)	0
Other comprehensive income (loss) before reclassification adjustments	(57)	(27)	(146)
Amounts reclassified from accumulated OCI	230
Tax benefit (provision)	(60)	9	51
Net other comprehensive income (loss)	113	(18)	(95)
Ending Balance	0	(113)	(95)
Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	154	(61)	0
Other comprehensive income (loss) before reclassification adjustments	(779)	330	(93)
Amounts reclassified from accumulated OCI	80
Tax benefit (provision)	83	(115)	32
Net other comprehensive income (loss)	(616)	215	(61)
Ending Balance	(462)	154	(61)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	136	(92)	68
Ending Balance	$ (214)	$ 136	$ (92)