Fair Value Measurements (Fair Value Of Deferred Annuities, Structured Settlements And Other Items) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of deferred annuities and structured settlements	$ 1,044	$ 1,045
Deferred Annuities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of deferred annuities and structured settlements	834	839
Structured Settlements
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of deferred annuities and structured settlements	210	206
Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of deferred annuities and structured settlements	0	0
Level 1 | Deferred Annuities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of deferred annuities and structured settlements	0	0
Level 1 | Structured Settlements
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of deferred annuities and structured settlements	0	0
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of deferred annuities and structured settlements	210	206
Level 2 | Deferred Annuities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of deferred annuities and structured settlements	0	0
Level 2 | Structured Settlements
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of deferred annuities and structured settlements	210	206
Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of deferred annuities and structured settlements	834	839
Level 3 | Deferred Annuities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of deferred annuities and structured settlements	834	839
Level 3 | Structured Settlements
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of deferred annuities and structured settlements	$ 0	$ 0