Accumulated other comprehensive income (loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	May 31, 2019	May 31, 2018	May 31, 2019	May 31, 2018
AOCI [Roll Forward]
Beginning Balance	$ 25,413	$ 28,178	$ 26,689	$ 28,274
Total other comprehensive income (loss)	(702)	(642)	(399)	266
Ending Balance	24,771	28,470	24,771	28,470
Pension/ post- retirement obligations
AOCI [Roll Forward]
Beginning Balance	95	(141)	101	(139)
Other comprehensive income (loss) before reclassification adjustments	1	0	1	(1)
Amounts reclassified from AOCI	(4)	(2)	(12)	(5)
Other			0
Tax benefit (provision)	1	0	3	2
Total other comprehensive income (loss)	(2)	(2)	(8)	(4)
Ending Balance	93	(143)	93	(143)
Unrealized gain (loss) on hedges
AOCI [Roll Forward]
Beginning Balance	(40)	(32)	(30)	(33)
Other comprehensive income (loss) before reclassification adjustments	56	0	40	0
Amounts reclassified from AOCI	1	1	4	3
Other			0
Tax benefit (provision)	(14)	0	(10)	(1)
Total other comprehensive income (loss)	44	1	33	2
Ending Balance	4	(31)	4	(31)
Share of AOCI of equity method investments
AOCI [Roll Forward]
Beginning Balance	2	0	3	(2)
Other comprehensive income (loss) before reclassification adjustments	1	3	(1)	7
Amounts reclassified from AOCI	0	11	0	11
Other			0
Tax benefit (provision)	0	(3)	0	(5)
Total other comprehensive income (loss)	1	11	(1)	13
Ending Balance	4	11	4	11
Cumulative translation adjustments
AOCI [Roll Forward]
Beginning Balance	(2,762)	(1,990)	(3,076)	(2,877)
Other comprehensive income (loss) before reclassification adjustments	(733)	(647)	(415)	240
Amounts reclassified from AOCI	0	8	0	8
Other			0
Tax benefit (provision)	1	0	(1)	0
Total other comprehensive income (loss)	(732)	(639)	(416)	248
Ending Balance	(3,493)	(2,629)	(3,493)	(2,629)
Accumulated other comprehensive income (loss)
AOCI [Roll Forward]
Beginning Balance	(2,705)	(2,163)	(3,002)	(3,051)
Other comprehensive income (loss) before reclassification adjustments	(675)	(644)	(376)	246
Amounts reclassified from AOCI	(2)	18	(8)	17
Other			0
Tax benefit (provision)	(12)	(3)	(8)	(4)
Total other comprehensive income (loss)	(689)	(629)	(393)	259
Ending Balance	$ (3,393)	$ (2,792)	$ (3,393)	$ (2,792)