Goodwill and intangible assets - Intangible Assets by Business Segment (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Intangible Assets [Roll Forward]
Beginning Balance				$ 3,012	$ 3,107
Disposition				(6)
Amortization	$ (19)	$ (20)	$ (26)	(63)	(78)
Foreign currency translation				(2)	(3)
Ending Balance	2,941		3,026	2,941	3,026
Investment Services
Intangible Assets [Roll Forward]
Beginning Balance				608	678
Disposition				0
Amortization				(41)	(54)
Foreign currency translation				0	1
Ending Balance	567		625	567	625
Investment and Wealth Management
Intangible Assets [Roll Forward]
Beginning Balance				1,555	1,580
Disposition				(6)
Amortization				(22)	(24)
Foreign currency translation				(2)	(4)
Ending Balance	1,525		1,552	1,525	1,552
Other
Intangible Assets [Roll Forward]
Beginning Balance				849	849
Disposition				0
Amortization				0	0
Foreign currency translation				0	0
Ending Balance	$ 849		$ 849	$ 849	$ 849