Loss And Loss Adjustment Expense Reserves (Schedule Of Insurance Loss Recoverable And Changes In Recoveries On Unpaid Losses) (Detail) (USD $) In Millions, unless otherwise specified			6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 Insurance Loss Recoverable And Changes In Recoveries On Unpaid Losses [Member]	Jun. 30, 2012 Insurance Loss Recoverable And Changes In Recoveries On Unpaid Losses [Member] Insurance Loss Recoverable [Member]	Jun. 30, 2012 Insurance Loss Recoverable And Changes In Recoveries On Unpaid Losses [Member] Recoveries On Unpaid Losses [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Gross Reserve beginning balance, Insurance loss recoverable	$ 3,212	$ 3,046
Gross Reserve beginning balance,Recoveries on unpaid losses	508	562
Gross Reserve beginning balance, Total	3,720	3,608
Gross Reserve ending balance, Insurance loss recoverable	3,212	3,046
Gross Reserve ending balance, Recoveries on unpaid losses	508	562
Gross Reserve ending balance, Total	3,720	3,608
Collections for Cases with Recoveries			(4)	(4)
Accretion of Recoveries			25	21	4
Changes in Discount Rates			26	9	17
Changes in Timing of Collections
Changes in Amount of Collections			(130)	(130)
Changes in Assumptions			186	257	(71)
Changes in LAE Recoveries			$ 9	$ 13	$ (4)