Income Taxes (Components Of Deferred Tax Assets and Liabilities) (Detail) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Deferred tax liabilities [Abstract]
Unearned premium reserve	$ 139	$ 143
Deferral of cancellation of indebtedness income	28	46
Deferred acquisition costs	34	42
Net gains on financial instruments at fair value and foreign exchange	0	4
Net unrealized gains in accumulated other comprehensive income	10	0
Partnership basis difference	29	36
Basis difference in foreign subsidiaries	1	64
Net deferred taxes on VIEs	13	0
Other	28	27
Total gross deferred tax liabilities	282	362
Deferred tax assets [Abstract]
Compensation and employee benefits	15	19
Accrued interest	208	177
Loss and loss adjustment expense reserves	121	142
Net operating loss	996	929
Foreign tax credit	62	7
Capital loss carryforward and other-than-temporary impairments	28	4
Net unrealized losses on insured derivatives	28	29
Net losses on financial instruments at fair value and foreign exchange	30	0
Net unrealized losses in accumulated other comprehensive income	0	6
Alternative minimum tax credit carryforward	30	26
Total gross deferred tax assets	1,518	1,339
Valuation allowance	1,236	7
Net deferred tax asset	$ 0	$ 970