Investments (Securities Pledged as Collateral Related to Repurchase Reverse Repurchase Program) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Assets Sold under Agreements to Repurchase [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	$ 55	$ 102
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	779	736
Obligation to Return Securities Received as Collateral	834	838
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	55	102
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	779	736
Obligation to Return Securities Received as Collateral	834	838
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	42	94
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	279	366
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	42	94
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	279	366
Residential Mortgage Backed Securities [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	0
Residential Mortgage Backed Securities [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	0
Residential Mortgage Backed Securities [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	0
Residential Mortgage Backed Securities [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	0
Residential Mortgage Backed Securities [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	0
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	10	5
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	373	370
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	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	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	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	10	5
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	373	370
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	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	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	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	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	3
Asset-backed Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	54	0
Asset-backed Securities [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	0
Asset-backed Securities [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	0
Asset-backed Securities [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	0
Asset-backed Securities [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	54	0
Commercial Mortgage Backed Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Financial Assets Sold under Agreements to Repurchase, Gross Including Not Subject to Master Netting Arrangement	63	0
Commercial Mortgage Backed Securities [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	0
Commercial Mortgage Backed Securities [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	0
Commercial Mortgage Backed Securities [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	0
Commercial Mortgage Backed Securities [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	$ 63	$ 0