Loss And Loss Adjustment Expense Reserves (Schedule Of Loss And Loss Adjustment Expenses Reserves) (Detail) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014
Loss And Loss Adjustment Expense Reserves [Line Items]
Changes in unearned premium revenue		$ 184	$ 204
Changes in LAE reserves		5	$ 87
Loss And Lae Reserves [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Gross loss and LAE reserve, beginning balance		506
Loss payments for cases with reserves		(21)
Accretion of claim liability discount		4
Changes in discount rates		(22)
Changes in assumptions		51
Changes in unearned premium revenue		3
Changes in LAE reserves		(5)
Other	[1]	(16)
Gross loss and LAE reserve, ending balance		$ 500

[1] Primarily changes in amount and timing of payments.