Loss And Loss Adjustment Expense Reserves (Schedule Of Insurance Loss Recoverable) (Detail) - Insurance Loss Recoverable [Member] - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019
Roll forward of Insurance Loss Recoverable [Line Items]
Gross Reserve beginning balance, Insurance loss recoverable		$ 1,694	$ 1,595
Collections for Cases		(49)	(148)
Accretion of Recoveries		14	35
Changes in Discount Rates		115	70
Changes in Assumptions	[1]	(94)	105
Other		(3)	37	[2]
Gross Reserve ending balance, Insurance loss recoverable		$ 1,677	$ 1,694

[1] Includes amounts related to paid claims and LAE that are expected to be recovered in the future.

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