Loss And Loss Adjustment Expense Reserves (Schedule Of Insurance Loss Recoverable And Changes In Recoveries On Unpaid Losses) (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2016 USD ($)
Insurance Loss Recoverable [Member]
Loss And Loss Adjustment Expense Recoveries [Line Items]
Gross Reserve beginning balance, Insurance loss recoverable	$ 577
Collections for Cases with Recoveries	(60)
Accretion of Recoveries	4
Changes in Discount Rates	9
Changes in Assumptions	58
Changes in LAE Recoveries	(5)
Other	(55)	[1]
Gross Reserve ending balance, Insurance loss recoverable	528
Recoveries On Unpaid Losses [Member]
Loss And Loss Adjustment Expense Recoveries [Line Items]
Gross Reserve beginning balance,Recoveries on unpaid losses	100
Collections for Cases with Recoveries	0
Accretion of Recoveries	1
Changes in Discount Rates	8
Changes in Assumptions	(31)
Changes in LAE Recoveries	5
Other	0	[1]
Gross Reserve ending balance, Recoveries on unpaid losses	83
Insurance Loss Recoverable And Changes In Recoveries On Unpaid Losses [Member]
Loss And Loss Adjustment Expense Recoveries [Line Items]
Gross Reserve beginning balance, Total	677
Collections for Cases with Recoveries	(60)
Accretion of Recoveries	5
Changes in Discount Rates	17
Changes in Assumptions	27
Changes in LAE Recoveries	0
Other	(55)	[1]
Gross Reserve ending balance, Total	$ 611

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