Investments (Securities Lending Remaining Tenor) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Securities Financing Transaction [Line Items]
Cash collateral received from counterparties	$ 3,731	$ 4,611
Remaining Tenor of Securities Lending Agreements: Open
Securities Financing Transaction [Line Items]
Cash collateral received from counterparties	642	1,095
Remaining Tenor of Securities Lending Agreements: 1 Month or Less
Securities Financing Transaction [Line Items]
Cash collateral received from counterparties	2,105	2,125
Remaining Tenor of Securities Lending Agreements: 1 to 6 Months
Securities Financing Transaction [Line Items]
Cash collateral received from counterparties	984	1,391
U.S. government and agency
Securities Financing Transaction [Line Items]
Cash collateral received from counterparties	3,151	4,610
U.S. government and agency | Remaining Tenor of Securities Lending Agreements: Open
Securities Financing Transaction [Line Items]
Cash collateral received from counterparties	640	1,094
U.S. government and agency | Remaining Tenor of Securities Lending Agreements: 1 Month or Less
Securities Financing Transaction [Line Items]
Cash collateral received from counterparties	1,527	2,125
U.S. government and agency | Remaining Tenor of Securities Lending Agreements: 1 to 6 Months
Securities Financing Transaction [Line Items]
Cash collateral received from counterparties	984	1,391
U.S. corporate
Securities Financing Transaction [Line Items]
Cash collateral received from counterparties	412	1
U.S. corporate | Remaining Tenor of Securities Lending Agreements: Open
Securities Financing Transaction [Line Items]
Cash collateral received from counterparties	2	1
U.S. corporate | Remaining Tenor of Securities Lending Agreements: 1 Month or Less
Securities Financing Transaction [Line Items]
Cash collateral received from counterparties	410	0
U.S. corporate | Remaining Tenor of Securities Lending Agreements: 1 to 6 Months
Securities Financing Transaction [Line Items]
Cash collateral received from counterparties	0	0
Foreign corporate
Securities Financing Transaction [Line Items]
Cash collateral received from counterparties	152	0
Foreign corporate | Remaining Tenor of Securities Lending Agreements: Open
Securities Financing Transaction [Line Items]
Cash collateral received from counterparties	0	0
Foreign corporate | Remaining Tenor of Securities Lending Agreements: 1 Month or Less
Securities Financing Transaction [Line Items]
Cash collateral received from counterparties	152	0
Foreign corporate | Remaining Tenor of Securities Lending Agreements: 1 to 6 Months
Securities Financing Transaction [Line Items]
Cash collateral received from counterparties	0	0
Foreign Government
Securities Financing Transaction [Line Items]
Cash collateral received from counterparties	16	0
Foreign Government | Remaining Tenor of Securities Lending Agreements: Open
Securities Financing Transaction [Line Items]
Cash collateral received from counterparties	0	0
Foreign Government | Remaining Tenor of Securities Lending Agreements: 1 Month or Less
Securities Financing Transaction [Line Items]
Cash collateral received from counterparties	16	0
Foreign Government | Remaining Tenor of Securities Lending Agreements: 1 to 6 Months
Securities Financing Transaction [Line Items]
Cash collateral received from counterparties	$ 0	$ 0