Investments (Schedule Of Average Carrying Value Of Impaired Mortgage Loans On Real Estate) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Information about impaired mortgage loans on real estate
Average carrying value for impaired mortgage loans on real estate	$ 6	$ 7	$ 17
Interest income recognized on impaired mortgage loans on real estate			1
Interest income collected on impaired mortgage loans on real estate			$ 1