Accumulated other comprehensive income (loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Feb. 28, 2022	Feb. 28, 2021	Feb. 28, 2022	Feb. 28, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 30,579	$ 20,563	$ 23,822	$ 21,136
Total other comprehensive (loss) income	(24)	385	(220)	476
Ending balance	30,867	21,625	30,867	21,625
Pension/ post-retirement obligations
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(364)	(736)	(359)	(748)
Other comprehensive income (loss) before reclassification adjustments	1	(1)	0	16
Amounts reclassified from AOCI	(5)	(2)	(11)	(4)
Other	(6)		(6)
Tax benefit (provision)	2	1	3	(3)
Total other comprehensive (loss) income	(8)	(2)	(13)	9
Ending balance	(372)	(739)	(372)	(739)
Unrealized gain (loss) on cash flow hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(9)	(27)	(10)	(31)
Other comprehensive income (loss) before reclassification adjustments	0	10	0	14
Amounts reclassified from AOCI	1	1	1	3
Other	0		0
Tax benefit (provision)	0	(3)	(1)	(4)
Total other comprehensive (loss) income	0	9	1	13
Ending balance	(9)	(18)	(9)	(18)
Net investment hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	9	(41)	(35)	(34)
Other comprehensive income (loss) before reclassification adjustments	(22)	(65)	31	(80)
Amounts reclassified from AOCI	0	0	0	0
Other	0		0
Tax benefit (provision)	2	16	(8)	24
Total other comprehensive (loss) income	(20)	(49)	24	(56)
Ending balance	(11)	(90)	(11)	(90)
Unrealized gain (loss) on AFS
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			96
Other comprehensive income (loss) before reclassification adjustments			450
Amounts reclassified from AOCI			(577)
Other			0
Tax benefit (provision)			31
Total other comprehensive (loss) income			(96)
Ending balance	0		0
Share of OCI of equity method investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(74)	(5)	(29)	(10)
Other comprehensive income (loss) before reclassification adjustments	(105)	13	(165)	19
Amounts reclassified from AOCI	0	0	0	0
Other	0		0
Tax benefit (provision)	26	2	40	1
Total other comprehensive (loss) income	(80)	15	(125)	20
Ending balance	(154)	10	(154)	10
Cumulative translation adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(1,863)	(2,873)	(1,772)	(2,948)
Other comprehensive income (loss) before reclassification adjustments	78	402	(9)	474
Amounts reclassified from AOCI	3	2	(1)	5
Other	0		0
Tax benefit (provision)	0	0	0	0
Total other comprehensive (loss) income	81	404	(10)	479
Ending balance	(1,782)	(2,469)	(1,782)	(2,469)
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(2,301)	(3,682)	(2,109)	(3,771)
Other comprehensive income (loss) before reclassification adjustments	(48)	359	307	444
Amounts reclassified from AOCI	(1)	1	(587)	4
Other	(6)		(6)
Tax benefit (provision)	29	16	66	17
Total other comprehensive (loss) income	(26)	376	(220)	465
Ending balance	$ (2,328)	$ (3,306)	$ (2,328)	$ (3,306)