Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	May 31, 2016	May 31, 2015	May 31, 2016	May 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			$ 31,300
Ending Balance	$ 31,314		31,314
Pension/Post-retirement Obligations [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	30	$ 6	29	$ 15
Other comprehensive income (loss) before reclassification adjustments	5	(2)	4	(12)
Amounts reclassified from accumulated OCI	0	0	0	0
Tax benefit (provision)	(2)	0	0	1
Net other comprehensive income (loss)	3	(2)	4	(11)
Ending Balance	33	4	33	4
Unrecognized Gain (Loss) on Available-for-Sale Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	172	296	259	107
Other comprehensive income (loss) before reclassification adjustments	(6)	115	(150)	412
Amounts reclassified from accumulated OCI	(268)	0	(268)	0
Tax benefit (provision)	102	(41)	159	(149)
Net other comprehensive income (loss)	(172)	74	(259)	263
Ending Balance	0	370	0	370
Unrealized Gain (Loss) on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(38)	(39)	(40)	(27)
Other comprehensive income (loss) before reclassification adjustments	0	2	0	(16)
Amounts reclassified from accumulated OCI	1	(2)	4	(3)
Tax benefit (provision)	(1)	0	(2)	7
Net other comprehensive income (loss)	0	0	2	(12)
Ending Balance	(38)	(39)	(38)	(39)
Share of Alliance Boots OCI [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		0		(113)
Other comprehensive income (loss) before reclassification adjustments		0		(57)
Amounts reclassified from accumulated OCI		0		230
Tax benefit (provision)		0		(60)
Net other comprehensive income (loss)		0		113
Ending Balance		0		0
Cumulative Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(2,032)	(331)	(462)	154
Other comprehensive income (loss) before reclassification adjustments	762	(145)	(808)	(793)
Amounts reclassified from accumulated OCI	(2)	0	(2)	80
Tax benefit (provision)	0	0	0	83
Net other comprehensive income (loss)	760	(145)	(810)	(630)
Ending Balance	(1,272)	(476)	(1,272)	(476)
AOCI Total [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(1,868)	(68)	(214)	136
Other comprehensive income (loss) before reclassification adjustments	761	(30)	(954)	(466)
Amounts reclassified from accumulated OCI	(269)	(2)	(266)	307
Tax benefit (provision)	99	(41)	157	(118)
Net other comprehensive income (loss)	591	(73)	(1,063)	(277)
Ending Balance	$ (1,277)	$ (141)	$ (1,277)	$ (141)