Derivative Financial Instruments (Effect Of Non-Hedging Derivatives On Income Statement And Included In Net Realized Gains (Losses) On Investments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Gain (Loss) Recognized	$ (2)	$ (17)	$ 23
Interest Rate Swaps [Member] | Net realized gains on financial instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Gain (Loss) Recognized	(1)	1	14
Options [Member] | Net realized gains on financial instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Gain (Loss) Recognized	(5)	(8)	1
Futures [Member] | Net realized gains on financial instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Gain (Loss) Recognized	$ 4	$ (10)	$ 8