Loss And Loss Adjustment Expense Reserves (Schedule Of Insurance Loss Recoverable And Changes In Recoveries On Unpaid Losses) (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Loss And Loss Adjustment Expense Recoveries [Line Items]
Gross Reserve beginning balance, Total	$ 1,583
Collections for Cases	(58)
Accretion of Recoveries	10
Changes in Discount Rates	29
Changes in Assumptions	39
Changes in LAE Recoveries	0
Other	(1)	[1]
Gross Reserve ending balance, Total	1,602
Insurance Loss Recoverable [Member]
Loss And Loss Adjustment Expense Recoveries [Line Items]
Gross Reserve beginning balance, Insurance loss recoverable	1,564
Collections for Cases	(58)
Accretion of Recoveries	10
Changes in Discount Rates	28
Changes in Assumptions	40	[2]
Changes in LAE Recoveries	0
Other	(1)	[1]
Gross Reserve ending balance, Insurance loss recoverable	1,583
Recoveries On Unpaid Losses [Member]
Loss And Loss Adjustment Expense Recoveries [Line Items]
Gross Reserve beginning balance,Recoveries on unpaid losses	19	[3]
Collections for Cases	0
Accretion of Recoveries	0	[3]
Changes in Discount Rates	1	[3]
Changes in Assumptions	(1)	[3]
Changes in LAE Recoveries	0	[3]
Other	0
Gross Reserve ending balance, Recoveries on unpaid losses	$ 19	[3]

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

[2] Includes amounts which have been paid and are expected to be recovered in the future.

[3] As of March 31, 2019 and December 31, 2018, excludes Puerto Rico recoveries, which have been netted against reserves.