Investments (Amortized Cost And Fair Value Of Fixed Maturity Securities, By Contractual Maturity) (Details) - Fixed Maturity Securities [Member] - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Amortized Cost
Due in one year or less, Amortized Cost	$ 543
Due after one year through five years, Amortized Cost	5,174
Due after five years through ten years, Amortized Cost	4,956
Due after ten years, Amortized Cost	3,869
Mortgage-backed securities, Amortized Cost	2,838
Available For Sale Securities, Amortized Cost	17,380	$ 17,610
Fair Value
Due in one year or less, Estimated Fair Value	544
Due after one year through five years, Estimated Fair Value	5,105
Due after five years through ten years, Estimated Fair Value	4,857
Due after ten years, Estimated Fair Value	3,856
Mortgage-backed securities, Estimated Fair Value	2,817
Available for sale securities Fair Value	$ 17,179	$ 17,938