Investments (Continuous Gross Unrealized Losses for Fixed Maturity Securities AFS by Sector - Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) Contracts	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Debt Securities, Available-for-sale [Line Items]
Change in gross unrealized losses of securities in an unrealized loss position	$ 3,167	$ (1,355)	$ 590
Fixed maturity securities available-for-sale with gross unrealized loss of equal to or greater than stated percentage	20.00%
Fixed maturity securities
Debt Securities, Available-for-sale [Line Items]
Change in gross unrealized losses of securities in an unrealized loss position	$ 1,200
Gross unrealized losses of securities in an unrealized loss position	166
20% or more | Six months or greater | Fixed maturity securities
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses of securities in an unrealized loss position	$ 9
Number of Securities | Contracts	12