Accumulated other comprehensive income (loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Aug. 31, 2021	Aug. 31, 2020	Aug. 31, 2019
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	$ 21,136	$ 24,152	$ 26,689
Total other comprehensive income (loss)	1,669	148	(909)
Ending Balance	23,822	21,136	24,152
Accumulated other comprehensive income (loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	(3,771)	(3,897)	(3,002)
Other comprehensive income (loss) before reclassification adjustments	1,022	(69)	(889)
Amounts reclassified from AOCI	6	0	(12)
Business disposal	792
Tax benefit (provision)	(157)	195	5
Total other comprehensive income (loss)	1,663	126	(896)
Ending Balance	(2,109)	(3,771)	(3,897)
Pension/post-retirement obligations
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	(748)	(48)	101
Other comprehensive income (loss) before reclassification adjustments	532	(861)	(162)
Amounts reclassified from AOCI	(8)	(8)	(17)
Business disposal	(4)
Tax benefit (provision)	(132)	169	30
Total other comprehensive income (loss)	389	(700)	(149)
Ending Balance	(359)	(748)	(48)
Unrealized gain (loss) on cash flow hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	(31)	(24)	(30)
Other comprehensive income (loss) before reclassification adjustments	10	(12)	1
Amounts reclassified from AOCI	17	5	5
Business disposal	0
Tax benefit (provision)	(6)	1	(1)
Total other comprehensive income (loss)	21	(6)	5
Ending Balance	(10)	(31)	(24)
Net investment hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	(34)	55	0
Other comprehensive income (loss) before reclassification adjustments	(6)	(113)	73
Amounts reclassified from AOCI	0	0	0
Business disposal	0
Tax benefit (provision)	6	23	(18)
Total other comprehensive income (loss)	(1)	(90)	55
Ending Balance	(35)	(34)	55
Unrealized gain (loss) on available for sale securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	0	0	0
Other comprehensive income (loss) before reclassification adjustments	127	0	0
Amounts reclassified from AOCI	0	0	0
Business disposal	0
Tax benefit (provision)	(31)	0	0
Total other comprehensive income (loss)	96	0	0
Ending Balance	96	0	0
Share of AOCI of equity method investments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	(10)	3	3
Other comprehensive income (loss) before reclassification adjustments	(24)	(16)	(1)
Amounts reclassified from AOCI	0	0	0
Business disposal	0
Tax benefit (provision)	6	3	0
Total other comprehensive income (loss)	(18)	(13)	(1)
Ending Balance	(29)	(10)	3
Cumulative translation adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	(2,948)	(3,884)	(3,076)
Other comprehensive income (loss) before reclassification adjustments	384	934	(801)
Amounts reclassified from AOCI	(3)	3	0
Business disposal	795
Tax benefit (provision)	0	(1)	(6)
Total other comprehensive income (loss)	1,176	936	(807)
Ending Balance	$ (1,772)	$ (2,948)	$ (3,884)