Investments (Fair Value Below Amortized Cost of Gross Unrealized Losses for Fixed Maturity Securities) (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Gross unrealized losses with number of securities [Line Items]
Document Period End Date	Jun. 30, 2020
Gross Unrealized Losses	$ 448	$ 110
% of Total	100.00%	100.00%
Less than 20%
Gross unrealized losses with number of securities [Line Items]
Gross Unrealized Losses	$ 348	$ 76
% of Total	77.70%	69.10%
20% or more for less than six months
Gross unrealized losses with number of securities [Line Items]
Gross Unrealized Losses	$ 91	$ 20
% of Total	20.30%	18.20%
20% or more for six months or greater
Gross unrealized losses with number of securities [Line Items]
Gross Unrealized Losses	$ 9	$ 14
% of Total	2.00%	12.70%