Investments (Average Carrying Value On The Impaired Mortgage Loans On Real Estate) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Information about impaired mortgage loans on real estate
Average carrying value for impaired loans on real estate	$ 7	$ 17	$ 24
Interest income recognized on impaired mortgage loans on real estate		1	2
Interest income collected on impaired mortgage loans on real estate		$ 1	$ 2