Commitments, contingencies, and guarantees Commitments, Contingencies, And Guarantees (Collateral pledged under repurchase agreements) (Details) - USD ($) $ in Millions		Jun. 30, 2022	Dec. 31, 2021
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements		$ 3,411	$ 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		3,582	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		45	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		104	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		3,425	1,288
Repurchase Agreements [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Secured Borrowings, Gross, Difference, Amount	[1]	171	14
Corporate and asset-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		8	0
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		1,654	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		21	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		104	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		1,521	0
Maturity 30 to 90 Days [Member] | Corporate and asset-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		8	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		1,928	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		24	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		1,904	1,288
Maturity Greater than 90 Days [Member] | Corporate and asset-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		$ 0	$ 0

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