Loss And Loss Adjustment Expense Reserves (Schedule Of Loss And Loss Adjustment Expenses Reserves) (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013
Loss And Loss Adjustment Expense Reserves [Line Items]
Changes in unearned premium revenue	$ 204		$ 265
Changes in LAE reserves	87		79
Loss And Lae Reserves [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Gross loss andLAE reserve, beginning balance	641
Loss payments for cases with reserves	(108)
Accretion of claim liability discount	8
Changes in discount rates	37
Changes in assumptions	(37)
Changes in unearned premium revenue	10
Changes in LAE reserves	11
Other	(8)	[1]
Gross loss andLAE reserve, ending balance	$ 554

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