Income Taxes (Components Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Loss and loss expense reserves	$ 66	$ 60
Unearned premiums	113	105
Deferred international earnings	51	0
Other	39	33
Deferred tax assets before valuation allowance	269	198
Valuation allowance for international operations	41	0
Deferred tax assets net of valuation allowance	228	198
Deferred tax liabilities:
Investment gains and other, net	995	542
Deferred acquisition costs	139	131
Life policy reserves	120	117
Investments	23	18
Other	30	17
Total gross deferred tax liabilities	1,307	825
Net deferred income tax liability	$ 1,079	$ 627