Investments (Average Carrying Value On The Impaired Mortgage Loans On Real Estate) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Information about impaired mortgage loans on real estate
Average carrying value for impaired mortgage loans on real estate	$ 5	$ 6	$ 5	$ 6