Business Segments (Summary Of Company's Segment Results) (Detail) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2022		Sep. 30, 2021		Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Segment Reporting Information [Line Items]
Revenues		$ 23	[1]	$ 52	[1]	$ 53	$ 115
Net gains (losses) on financial instruments at fair value and foreign exchange		25		9		51	41
Net gains (losses) on extinguishment of debt				16		4	30
Revenues of consolidated VIEs		(31)		(5)		(11)	(24)
Inter-segment revenues		0	[2]	0		0	0
Total revenues		17		72		97	162
Losses and loss adjustment		(12)		125		57	232
Amortization of deferred acquisition costs and operating		16		23		49	75
Interest		46		40		130	122
Expenses of consolidated VIEs		2		7		5	23
Inter-segment expenses		0	[2]	0	[2]	0	0
Total expenses		52		195		241	452
Income (loss) from continuing operations before income taxes		(35)		(123)		(144)	(290)
Identifiable assets per segment		3,883				3,883
Assets held for sale		132				132
Total identifiable assets		4,015				4,015		$ 4,696
Operating Segments [Member] | US Public Finance Insurance [Member]
Segment Reporting Information [Line Items]
Revenues		17	[1]	21	[1]	24	65
Net gains (losses) on financial instruments at fair value and foreign exchange		(6)		0		(43)	0
Net gains (losses) on extinguishment of debt				0		0	0
Revenues of consolidated VIEs		0		0		0	0
Inter-segment revenues		6	[2]	8		20	22
Total revenues		17		29		1	87
Losses and loss adjustment		16		68		152	135
Amortization of deferred acquisition costs and operating		2		6		6	14
Interest		0		0		0	0
Expenses of consolidated VIEs		0		0		0	0
Inter-segment expenses		10	[2]	11	[2]	33	36
Total expenses		28		85		191	185
Income (loss) from continuing operations before income taxes		(11)		(56)		(190)	(98)
Identifiable assets per segment		3,061				3,061
Assets held for sale		0				0
Total identifiable assets		3,061				3,061
Operating Segments [Member] | Corporate Operations [Member]
Segment Reporting Information [Line Items]
Revenues		(3)	[1]	7	[1]	3	13
Net gains (losses) on financial instruments at fair value and foreign exchange		35		12		111	50
Net gains (losses) on extinguishment of debt				16		5	30
Revenues of consolidated VIEs		0		0		0	0
Inter-segment revenues		12	[2]	14		43	50
Total revenues		44		49		162	143
Losses and loss adjustment		0		0		0	0
Amortization of deferred acquisition costs and operating		12		16		35	54
Interest		14		14		42	42
Expenses of consolidated VIEs		0		0		0	0
Inter-segment expenses		5	[2]	4	[2]	17	14
Total expenses		31		34		94	110
Income (loss) from continuing operations before income taxes		13		15		68	33
Identifiable assets per segment		622				622
Assets held for sale		0				0
Total identifiable assets		622				622
Operating Segments [Member] | International And Structured Finance Insurance [Member]
Segment Reporting Information [Line Items]
Revenues		9	[1]	24	[1]	26	37
Net gains (losses) on financial instruments at fair value and foreign exchange		(4)		(3)		(17)	(9)
Net gains (losses) on extinguishment of debt				0		0	0
Revenues of consolidated VIEs		(31)		(5)		(11)	(24)
Inter-segment revenues		2	[2]	2		7	10
Total revenues		(24)		18		5	14
Losses and loss adjustment		(28)		57		(95)	97
Amortization of deferred acquisition costs and operating		2		1		8	7
Interest		32		26		88	80
Expenses of consolidated VIEs		2		7		5	23
Inter-segment expenses		6	[2]	9	[2]	20	30
Total expenses		14		100		26	237
Income (loss) from continuing operations before income taxes		(38)		(82)		(21)	(223)
Identifiable assets per segment		1,708				1,708
Assets held for sale		0				0
Total identifiable assets		1,708				1,708
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Revenues		0	[1]	0	[1]	0	0
Net gains (losses) on financial instruments at fair value and foreign exchange		0		0		0	0
Net gains (losses) on extinguishment of debt				0		(1)	0
Revenues of consolidated VIEs		0		0		0	0
Inter-segment revenues		(20)	[2]	(24)		(70)	(82)
Total revenues		(20)		(24)		(71)	(82)
Losses and loss adjustment		0		0		0	0
Amortization of deferred acquisition costs and operating		0		0		0	0
Interest		0		0		0	0
Expenses of consolidated VIEs		0		0		0	0
Inter-segment expenses		(21)	[2]	(24)	[2]	(70)	(80)
Total expenses		(21)		(24)		(70)	(80)
Income (loss) from continuing operations before income taxes		1		$ 0		(1)	$ (2)
Identifiable assets per segment	[3]	(1,508)				(1,508)
Assets held for sale		0				0
Total identifiable assets		$ (1,508)				$ (1,508)

[1] Consists of net premiums earned, net investment income, net realized investment gains (losses), fees and reimbursements and other net realized gains (losses).

[2] Primarily represents intercompany service charges and intercompany net investment income and expenses.

[3] Consists principally of intercompany reinsurance balances.