Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	May. 31, 2015	May. 31, 2014	May. 31, 2015	May. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	$ (68)	$ 174	$ 136	$ (92)
Other comprehensive income (loss) before reclassification adjustments	(30)	176	(466)	563
Amounts reclassified from accumulated OCI	(2)		307
Tax benefit (provision)	(41)	(78)	(118)	(199)
Net other comprehensive income (loss)	(73)	98	(277)	364
Balance	(141)	272	(141)	272
Post-retirement Liability [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	6	69	15	63
Other comprehensive income (loss) before reclassification adjustments	(2)	(3)	(12)	6
Amounts reclassified from accumulated OCI	0		0
Tax benefit (provision)	0	1	1	(2)
Net other comprehensive income (loss)	(2)	(2)	(11)	4
Balance	4	67	4	67
Unrecognized Gains on Available-for-Sale Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	296	36	107	1
Other comprehensive income (loss) before reclassification adjustments	115	63	412	120
Amounts reclassified from accumulated OCI	0		0
Tax benefit (provision)	(41)	(23)	(149)	(45)
Net other comprehensive income (loss)	74	40	263	75
Balance	370	76	370	76
Unrealized Loss on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(39)	0	(27)	0
Other comprehensive income (loss) before reclassification adjustments	2	(21)	(16)	(21)
Amounts reclassified from accumulated OCI	(2)		(3)
Tax benefit (provision)	0	8	7	8
Net other comprehensive income (loss)	0	(13)	(12)	(13)
Balance	(39)	(13)	(39)	(13)
Share of Alliance Boots OCI [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	0	(151)	(113)	(95)
Other comprehensive income (loss) before reclassification adjustments	0	75	(57)	(11)
Amounts reclassified from accumulated OCI	0		230
Tax benefit (provision)	0	(26)	(60)	4
Net other comprehensive income (loss)	0	49	113	(7)
Balance	0	(102)	0	(102)
Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(331)	220	154	(61)
Other comprehensive income (loss) before reclassification adjustments	(145)	62	(793)	469
Amounts reclassified from accumulated OCI	0		80
Tax benefit (provision)	0	(38)	83	(164)
Net other comprehensive income (loss)	(145)	24	(630)	305
Balance	$ (476)	$ 244	$ (476)	$ 244