Income Taxes (Components Of Deferred Tax Assets and Liabilities) (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deferred tax liabilities [Abstract]
Unearned premium reserve	$ 59	$ 75
Deferral of cancellation of indebtedness income	0	14
Deferred acquisition costs	16	21
Net unrealized gains in accumulated other comprehensive income	0	0
Partnership basis difference	3	11
Basis difference in foreign subsidiaries	0	1
Net deferred taxes on VIEs	55	38
Other	0	0
Total gross deferred tax liabilities	133	160
Deferred tax assets [Abstract]
Compensation and employee benefits	7	11
Accrued interest	158	131
Loss and loss adjustment expense reserves	135	87
Net operating loss	512	582
Foreign tax credit	62	62
Capital loss carryforward and other-than-temporary impairments	22	22
Net unrealized losses on insured derivatives	8	14
Net losses on financial instruments at fair value and foreign exchange	30	13
Net unrealized losses in accumulated other comprehensive income	32	5
Alternative minimum tax credit carryforward	0	0
Other	1	3
Total gross deferred tax assets	967	930
Valuation allowance	834	770
Net deferred tax asset	$ 0	$ 0