Investments Investments (Details) - Concentrations and Credit Quality - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Investment disclosure details
Fixed maturities, at fair value	$ 74,003	$ 68,134
Below investment grade [Member]
Investment disclosure details
Fixed maturities, at fair value	1,340	1,460
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]
Investment disclosure details
Fixed maturities, at fair value	$ 2,149	$ 2,095
Credit Concentration Risk [Member] | Shareholders' equity, total [Member] | U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member] | Minimum [Member]
Investment disclosure details
Concentration risk as a percentage of shareholders' equity	5.00%	5.00%