Accumulated other comprehensive income (loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2018	May 31, 2017
AOCI [Roll Forward]
Beginning Balance			$ 28,274	$ 30,281
Net other comprehensive income (loss)	$ (642)	$ 511	266	(349)
Ending Balance	28,470	31,484	28,470	31,484
Pension/ post- retirement obligations
AOCI [Roll Forward]
Beginning Balance	(141)	(216)	(139)	(212)
Other comprehensive income (loss) before reclassification adjustments	0	(102)	(1)	(107)
Amounts reclassified from accumulated OCI	(2)	109	(5)	109
Tax benefit (provision)	0	(2)	2	(1)
Net other comprehensive income (loss)	(2)	5	(4)	1
Ending Balance	(143)	(211)	(143)	(211)
Unrecognized gain (loss) on available-for- sale investments
AOCI [Roll Forward]
Beginning Balance	0	1	0	2
Other comprehensive income (loss) before reclassification adjustments	0	(1)	0	(2)
Amounts reclassified from accumulated OCI	0	0	0	0
Tax benefit (provision)	0	0	0	0
Net other comprehensive income (loss)	0	(1)	0	(2)
Ending Balance	0	0	0	0
Unrealized gain (loss) on cash flow hedges
AOCI [Roll Forward]
Beginning Balance	(32)	(35)	(33)	(37)
Other comprehensive income (loss) before reclassification adjustments	0	0	0	0
Amounts reclassified from accumulated OCI	1	1	3	4
Tax benefit (provision)	0	0	(1)	(1)
Net other comprehensive income (loss)	1	1	2	3
Ending Balance	(31)	(34)	(31)	(34)
Share of OCI of equity method investments
AOCI [Roll Forward]
Beginning Balance	0	(6)	(2)	(1)
Other comprehensive income (loss) before reclassification adjustments	3	4	7	(4)
Amounts reclassified from accumulated OCI	11	0	11	0
Tax benefit (provision)	(3)	(2)	(5)	1
Net other comprehensive income (loss)	11	2	13	(3)
Ending Balance	11	(4)	11	(4)
Currency translation adjustment
AOCI [Roll Forward]
Beginning Balance	(1,990)	(3,553)	(2,877)	(2,744)
Other comprehensive income (loss) before reclassification adjustments	(647)	499	240	(310)
Amounts reclassified from accumulated OCI	8	0	8	0
Tax benefit (provision)	0	0	0	0
Net other comprehensive income (loss)	(639)	499	248	(310)
Ending Balance	(2,629)	(3,054)	(2,629)	(3,054)
Accumulated other comprehensive (loss) income
AOCI [Roll Forward]
Beginning Balance	(2,163)	(3,809)	(3,051)	(2,992)
Other comprehensive income (loss) before reclassification adjustments	(644)	400	246	(423)
Amounts reclassified from accumulated OCI	18	110	17	113
Tax benefit (provision)	(3)	(4)	(4)	(1)
Net other comprehensive income (loss)	(629)	506	259	(311)
Ending Balance	$ (2,792)	$ (3,303)	$ (2,792)	$ (3,303)