Investments (Securities Lending and Repurchase Agreements Remaining Tenor) (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	$ 21,077	$ 21,055
U.S. government and agency
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	19,985	20,007
Foreign government
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	1,043	1,047
RMBS
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	49	0
U.S. corporate
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	0	1
Open (1)
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	5,873	5,901
Open (1) | U.S. government and agency
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	5,873	5,900
Open (1) | Foreign government
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	0	0
Open (1) | RMBS
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	0	0
Open (1) | U.S. corporate
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	0	1
1 Month or Less
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	6,720	7,337
1 Month or Less | U.S. government and agency
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	6,392	7,052
1 Month or Less | Foreign government
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	328	285
1 Month or Less | RMBS
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	0	0
1 Month or Less | U.S. corporate
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	0	0
Over 1 Month to 6 Months
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	8,484	7,817
Over 1 Month to 6 Months | U.S. government and agency
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	7,720	7,055
Over 1 Month to 6 Months | Foreign government
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	715	762
Over 1 Month to 6 Months | RMBS
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	49	0
Over 1 Month to 6 Months | U.S. corporate
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	0	0
Over 6 Months to 1 Year
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	0	0
Over 6 Months to 1 Year | U.S. government and agency
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	0	0
Over 6 Months to 1 Year | Foreign government
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	0	0
Over 6 Months to 1 Year | RMBS
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	0	0
Over 6 Months to 1 Year | U.S. corporate
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	0	0
Repurchase Agreements
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	3,325	3,325
Repurchase Agreements | U.S. government and agency
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	3,325	3,325
Repurchase Agreements | Open (1) | U.S. government and agency
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	0	0
Repurchase Agreements | 1 Month or Less | U.S. government and agency
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	3,325	3,325
Repurchase Agreements | Over 1 Month to 6 Months | U.S. government and agency
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	0	0
Repurchase Agreements | Over 6 Months to 1 Year | U.S. government and agency
Securities Financing Transaction [Line Items]
Cash collateral on deposit from counterparties	$ 0	$ 0