Commitments, contingencies, and guarantees Commitments, Contingencies, And Guarantees (Collateral pledged under repurchase agreements) (Details) - USD ($) $ in Millions		Sep. 30, 2022	Dec. 31, 2021
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements		$ 2,417	$ 1,406
Asset Pledged as Collateral without Right
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements		2,529	1,420
Cash [Member] | Asset Pledged as Collateral without Right
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements		76	29
U.S. Treasury / Agency | Asset Pledged as Collateral without Right
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements		102	103
Mortgage-backed securities | Asset Pledged as Collateral without Right
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements		2,351	1,288
Repurchase Agreements [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Secured Borrowings, Gross, Difference, Amount	[1]	112	14
Maturity Less than 30 Days [Member] | Asset Pledged as Collateral without Right
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements		416
Maturity Less than 30 Days [Member] | Cash [Member] | Asset Pledged as Collateral without Right
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements		66
Maturity Less than 30 Days [Member] | U.S. Treasury / Agency | Asset Pledged as Collateral without Right
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements		0
Maturity Less than 30 Days [Member] | Mortgage-backed securities | Asset Pledged as Collateral without Right
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements		350
Maturity 30 to 90 Days [Member] | Asset Pledged as Collateral without Right
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements		1,642	103
Maturity 30 to 90 Days [Member] | Cash [Member] | Asset Pledged as Collateral without Right
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements		10	0
Maturity 30 to 90 Days [Member] | U.S. Treasury / Agency | Asset Pledged as Collateral without Right
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements		102	103
Maturity 30 to 90 Days [Member] | Mortgage-backed securities | Asset Pledged as Collateral without Right
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements		1,530	0
Maturity Greater than 90 Days [Member] | Asset Pledged as Collateral without Right
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements		471	1,317
Maturity Greater than 90 Days [Member] | Cash [Member] | Asset Pledged as Collateral without Right
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements		0	29
Maturity Greater than 90 Days [Member] | U.S. Treasury / Agency | Asset Pledged as Collateral without Right
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements		0	0
Maturity Greater than 90 Days [Member] | Mortgage-backed securities | Asset Pledged as Collateral without Right
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements		$ 471	$ 1,288

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