Loss And Loss Adjustment Expense Reserves (Schedule Of Loss And Loss Adjustment Expenses Reserves) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Loss And Loss Adjustment Expense Reserves [Line Items]
Changes in unearned premium revenue	$ 506		$ 600		$ 624
Changes in LAE reserves	216		(17)		293
Loss And Lae Reserves [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Gross loss andLAE reserve, beginning balance	853		836
Loss payments for cases with reserves	(337)		(395)
Accretion of claim liability discount	13		11
Changes in discount rates	(92)		(26)
Changes in assumptions	141		319
Changes in unearned premium revenue	12		2
Changes in LAE reserves	(2)		8
Other	53	[1]	98	[1]
Gross loss andLAE reserve, ending balance	$ 641		$ 853

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