Expenses - Restructuring Reserve (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Restructuring Reserve [Roll Forward]
Beginning balance	$ 74	$ 196
Accruals		2
Payments and Other Adjustments	(18)	(11)
Ending balance	56	186
State Street Beacon
Restructuring Reserve [Roll Forward]
Accruals		(1)
Employee Related Costs
Restructuring Reserve [Roll Forward]
Beginning balance	68	190
Accruals		0
Payments and Other Adjustments	(17)	(9)
Ending balance	51	180
Employee Related Costs | State Street Beacon
Restructuring Reserve [Roll Forward]
Accruals		(1)
Real Estate Actions
Restructuring Reserve [Roll Forward]
Beginning balance	6	6
Accruals		2
Payments and Other Adjustments	(1)	(2)
Ending balance	5	6
Real Estate Actions | State Street Beacon
Restructuring Reserve [Roll Forward]
Accruals		0
Asset and Other Write-offs
Restructuring Reserve [Roll Forward]
Beginning balance	0	0
Accruals		0
Payments and Other Adjustments	0	0
Ending balance	$ 0	0
Asset and Other Write-offs | State Street Beacon
Restructuring Reserve [Roll Forward]
Accruals		$ 0