Investments (Securities Pledged as Collateral Related to Repurchase Reverse Repurchase Program) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	$ 102	$ 105
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	746	711
Securities Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	830	771
Secured Borrowings, Gross, Difference, Amount	18	45
Obligation to Return Securities Received as Collateral	848	816
Maturity Overnight [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	0	0
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	0	0
Obligation to Return Securities Received as Collateral	0	0
Maturity Less than 30 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	0	0
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	0	0
Obligation to Return Securities Received as Collateral	0	0
Maturity 30 to 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	0	0
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	0	0
Obligation to Return Securities Received as Collateral	0	0
Maturity Greater than 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	102	105
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	746	711
Obligation to Return Securities Received as Collateral	848	816
Corporate Debt Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	94	105
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	366	417
Corporate Debt Securities [Member] | Maturity Overnight [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	0	0
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	0	0
Corporate Debt Securities [Member] | Maturity Less than 30 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	0	0
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	0	0
Corporate Debt Securities [Member] | Maturity 30 to 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	0	0
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	0	0
Corporate Debt Securities [Member] | Maturity Greater than 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	94	105
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	366	417
Debt Security, Government, Non-US [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	5
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	370	294
Debt Security, Government, Non-US [Member] | Maturity Overnight [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	0
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	0	0
Debt Security, Government, Non-US [Member] | Maturity Less than 30 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	0
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	0	0
Debt Security, Government, Non-US [Member] | Maturity 30 to 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	0
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	0	0
Debt Security, Government, Non-US [Member] | Maturity Greater than 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	5
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	370	$ 294
US States and Political Subdivisions Debt Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	3
US States and Political Subdivisions Debt Securities [Member] | Maturity Overnight [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	0
US States and Political Subdivisions Debt Securities [Member] | Maturity Less than 30 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	0
US States and Political Subdivisions Debt Securities [Member] | Maturity 30 to 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	0
US States and Political Subdivisions Debt Securities [Member] | Maturity Greater than 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	3
Cash and Cash Equivalents [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	10
Cash and Cash Equivalents [Member] | Maturity Overnight [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	0
Cash and Cash Equivalents [Member] | Maturity Less than 30 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	0
Cash and Cash Equivalents [Member] | Maturity 30 to 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	0
Cash and Cash Equivalents [Member] | Maturity Greater than 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	$ 10