Goodwill and intangible assets - Intangible Assets by Business Segment (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Intangible Assets [Roll Forward]
Beginning Balance		$ 3,107		$ 3,107	$ 3,220
Amortization	$ (26)	(26)	$ (30)	(52)	(59)
Foreign currency translation				(10)	(1)
Ending Balance	3,045		3,160	3,045	3,160
Investment Services
Intangible Assets [Roll Forward]
Beginning Balance		678		678	758
Amortization				(36)	(41)
Foreign currency translation				0	0
Ending Balance	642		717	642	717
Investment and Wealth Management
Intangible Assets [Roll Forward]
Beginning Balance		1,580		1,580	1,613
Amortization				(16)	(18)
Foreign currency translation				(10)	(1)
Ending Balance	1,554		1,594	1,554	1,594
Other
Intangible Assets [Roll Forward]
Beginning Balance		$ 849		849	849
Amortization				0	0
Foreign currency translation				0	0
Ending Balance	$ 849		$ 849	$ 849	$ 849