Investments Investments (Details) - Concentrations and Credit Quality - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Investment disclosure details
Fixed maturities, at fair value	$ 68,134	$ 63,464
Below investment grade [Member]
Investment disclosure details
Fixed maturities, at fair value	1,460	1,480
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]
Investment disclosure details
Fixed maturities, at fair value	$ 2,095	$ 2,064
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%