Accumulated other comprehensive income (loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Nov. 30, 2018	Nov. 30, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 26,689	$ 28,274
Total other comprehensive income (loss)	(232)	522
Ending Balance	26,263	26,756
Pension/ post-retirement obligations
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	101	(139)
Other comprehensive income (loss) before reclassification adjustments	0	(1)
Amounts reclassified from AOCI	(4)	0
Tax benefit (provision)	0	1
Total other comprehensive income (loss)	(4)	0
Ending Balance	97	(139)
Unrecognized gain (loss) on available-for-sale investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	0	0
Other comprehensive income (loss) before reclassification adjustments	0	0
Amounts reclassified from AOCI	0	0
Tax benefit (provision)	0	0
Total other comprehensive income (loss)	0	0
Ending Balance	0	0
Unrealized gain (loss) on hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(30)	(33)
Other comprehensive income (loss) before reclassification adjustments	3	0
Amounts reclassified from AOCI	1	1
Tax benefit (provision)	(1)	(1)
Total other comprehensive income (loss)	3	0
Ending Balance	(27)	(33)
Share of AOCI of equity method investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	3	(2)
Other comprehensive income (loss) before reclassification adjustments	1	3
Amounts reclassified from AOCI	0	0
Tax benefit (provision)	0	(1)
Total other comprehensive income (loss)	1	2
Ending Balance	4	0
Cumulative translation adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(3,076)	(2,877)
Other comprehensive income (loss) before reclassification adjustments	(228)	506
Amounts reclassified from AOCI	0	0
Tax benefit (provision)	(1)	0
Total other comprehensive income (loss)	(229)	506
Ending Balance	(3,305)	(2,371)
Accumulated other comprehensive income (loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(3,002)	(3,051)
Other comprehensive income (loss) before reclassification adjustments	(224)	508
Amounts reclassified from AOCI	(3)	1
Tax benefit (provision)	(2)	(1)
Total other comprehensive income (loss)	(229)	508
Ending Balance	$ (3,231)	$ (2,543)