Income Taxes (Components Of Deferred Tax Assets and Liabilities) (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deferred tax liabilities:
Unearned premium reserve	$ 54	$ 59
Deferred acquisition costs	13	16
Partnership basis difference	0	3
Net deferred taxes on VIEs	51	55
Other	4	0
Total gross deferred tax liabilities	122	133
Deferred tax assets:
Compensation and employee benefits	8	7
Accrued interest	185	158
Partnership basis difference	10
Loss and loss adjustment expense reserves	101	135
Net operating loss	590	512
Foreign tax credits	61	62
Other-than-temporary impairments	2	22
Net unrealized losses on insured derivatives	9	8
Net losses on financial instruments at fair value and foreign exchange	21	30
Net unrealized losses in accumulated other comprehensive income	0	32
Other	8	1
Total gross deferred tax assets	995	967
Valuation allowance	873	834
Net deferred tax asset	$ 0	$ 0