Income Taxes (Components Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Loss and loss expense reserves	$ 60	$ 123
Unearned premiums	105	100
Other	33	27
Total gross deferred tax assets	198	250
Deferred tax liabilities:
Investment gains and other, net	542	740
Deferred acquisition costs	131	123
Life policy reserves	117	111
Investments	18	10
Other	17	11
Total gross deferred tax liabilities	825	995
Net deferred income tax liability	$ 627	$ 745