Investments (Equity Securities) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 1,105	$ 1,342
Percentage of Equity Securities	100.00%	100.00%
Equity Securities
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 1,105	$ 1,342
Common Stock
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 739	$ 944
Percentage of Equity Securities	66.90%	70.30%
Non-redeemable Preferred Stock
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 366	$ 398
Percentage of Equity Securities	33.10%	29.70%