Accumulated other comprehensive income (loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Nov. 30, 2017	Nov. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 28,274	$ 30,281
Net other comprehensive income (loss)	522	(865)
Ending Balance	26,756	29,692
Pension/ post- retirement obligations
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(139)	(212)
Other comprehensive income (loss) before reclassification adjustments	(1)	(11)
Amounts reclassified from accumulated OCI	0
Tax benefit (provision)	1	2
Net other comprehensive income (loss)	0	(9)
Ending Balance	(139)	(221)
Unrecognized gain (loss) on available-for- sale investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	0	2
Other comprehensive income (loss) before reclassification adjustments	0	(1)
Amounts reclassified from accumulated OCI	0
Tax benefit (provision)	0	0
Net other comprehensive income (loss)	0	(1)
Ending Balance	0	1
Unrealized gain (loss) on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(33)	(37)
Other comprehensive income (loss) before reclassification adjustments	0	1
Amounts reclassified from accumulated OCI	1
Tax benefit (provision)	(1)	0
Net other comprehensive income (loss)	0	1
Ending Balance	(33)	(36)
Share of OCI of equity method investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(2)	(1)
Other comprehensive income (loss) before reclassification adjustments	3	(1)
Amounts reclassified from accumulated OCI	0
Tax benefit (provision)	(1)	0
Net other comprehensive income (loss)	2	(1)
Ending Balance	0	(2)
Currency translation adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(2,877)	(2,744)
Other comprehensive income (loss) before reclassification adjustments	506	(808)
Amounts reclassified from accumulated OCI	0
Tax benefit (provision)	0	0
Net other comprehensive income (loss)	506	(808)
Ending Balance	(2,371)	(3,552)
Total
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(3,051)	(2,992)
Other comprehensive income (loss) before reclassification adjustments	508	(820)
Amounts reclassified from accumulated OCI	1
Tax benefit (provision)	(1)	2
Net other comprehensive income (loss)	508	(818)
Ending Balance	$ (2,543)	$ (3,810)