Goodwill and intangible assets - Intangible Assets by Business Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Intangible Assets [Roll Forward]
Beginning balance			$ 2,822	$ 2,851
Business realignment			0
Amortization	$ (10)	$ (11)	(19)	(22)
Foreign currency translation			(3)	20
Ending balance	2,800	2,849	2,800	2,849
Securities Services
Intangible Assets [Roll Forward]
Business realignment			(44)
Securities Services \| Operating segments
Intangible Assets [Roll Forward]
Beginning balance			164	186
Amortization			(11)	(13)
Foreign currency translation			(1)	5
Ending balance	108	178	108	178
Market and Wealth Services
Intangible Assets [Roll Forward]
Business realignment			44
Market and Wealth Services \| Operating segments
Intangible Assets [Roll Forward]
Beginning balance			371	374
Amortization			(2)	(1)
Foreign currency translation			0	0
Ending balance	413	373	413	373
Investment and Wealth Management
Intangible Assets [Roll Forward]
Business realignment			0
Investment and Wealth Management \| Operating segments
Intangible Assets [Roll Forward]
Beginning balance			1,438	1,442
Amortization			(6)	(8)
Foreign currency translation			(2)	15
Ending balance	1,430	1,449	1,430	1,449
Other
Intangible Assets [Roll Forward]
Business realignment			0
Other \| Operating segments
Intangible Assets [Roll Forward]
Beginning balance			849	849
Amortization			0	0
Foreign currency translation			0	0
Ending balance	$ 849	$ 849	$ 849	$ 849