Commitments, contingencies, and guarantees Commitments, contingencies, and guarantees (Collateral pledged under repurchase agreements) (Details) - USD ($) $ in Millions		Dec. 31, 2021	Dec. 31, 2020
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements		$ 1,420	$ 1,462
Securities Sold under Agreements to Repurchase		1,406	1,405
Cash
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements		29	4
US Treasury and Government [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements		103	106
Mortgage-backed securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements		1,288	1,352
Repurchase Agreements [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Secured Borrowings, Gross, Difference, Amount	[1]	14	57
Maturity 30 to 90 Days [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements		103	481
Maturity 30 to 90 Days [Member] | Cash
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements		0	0
Maturity 30 to 90 Days [Member] | US Treasury and Government [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements		103	0
Maturity 30 to 90 Days [Member] | Mortgage-backed securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements		0	481
Maturity Greater than 90 Days [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements		1,317	981
Maturity Greater than 90 Days [Member] | Cash
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements		29	4
Maturity Greater than 90 Days [Member] | US Treasury and Government [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements		0	106
Maturity Greater than 90 Days [Member] | Mortgage-backed securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Collateral pledged under repurchase agreements		$ 1,288	$ 871

[1] Per the repurchase agreements, the amount of collateral posted is required to exceed the amount of gross liability