Investments (Equity Securities) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 1,079	$ 1,342
Percentage of Equity Securities	100.00%	100.00%
Equity securities
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 1,079	$ 1,342
Common Stock
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 779	$ 944
Percentage of Equity Securities	72.20%	70.30%
Non-redeemable Preferred Stock
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 300	$ 398
Percentage of Equity Securities	27.80%	29.70%