Business Segments (Summary Of Company's Segment Results) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022		Dec. 31, 2021		Dec. 31, 2020
Segment Reporting Information [Line Items]
Revenues	$ 100	[1]	$ 142	[1]	$ 199
Net gains (losses) on financial instruments at fair value and foreign exchange	45		40		(80)
Net gains (losses) on extinguishment of debt	4		30
Revenues of consolidated VIEs	5		(23)		163
Inter-segment revenues	0	[2]	0	[2]	0
Total revenues	154		189		282
Losses and loss adjustment	38		350		530
Amortization of deferred acquisition costs and operating	76		97		97
Interest	179		163		178
Expenses of consolidated VIEs	9		24		55
Inter-segment expenses	0	[2]	0	[2]	0	[3]
Total expenses	302		634		860
Income (loss) from continuing operations before income taxes	(148)		(445)		(578)
Identifiable assets per segment	3,295
Assets held for sale	80
Identifiable assets	3,375		4,696
Operating Segments [Member] | US Public Finance Insurance [Member]
Segment Reporting Information [Line Items]
Revenues	53	[1]	85	[1]	138
Net gains (losses) on financial instruments at fair value and foreign exchange	(47)		(2)		2
Net gains (losses) on extinguishment of debt	0		0
Revenues of consolidated VIEs	0		0		0
Inter-segment revenues	29	[2]	27	[2]	28
Total revenues	35		110		168
Losses and loss adjustment	143		227		163
Amortization of deferred acquisition costs and operating	8		17		14
Interest	0		0		0
Expenses of consolidated VIEs	0		0		0
Inter-segment expenses	44	[2]	45	[2]	45	[3]
Total expenses	195		289		222
Income (loss) from continuing operations before income taxes	(160)		(179)		(54)
Identifiable assets per segment	2,491
Assets held for sale	0
Identifiable assets	2,491		3,313
Operating Segments [Member] | Corporate Operations [Member]
Segment Reporting Information [Line Items]
Revenues	8	[1]	13	[1]	31
Net gains (losses) on financial instruments at fair value and foreign exchange	99		56		(74)
Net gains (losses) on extinguishment of debt	5		30
Revenues of consolidated VIEs	0		0		0
Inter-segment revenues	55	[2]	67	[2]	66
Total revenues	167		166		23
Losses and loss adjustment	0		0		0
Amortization of deferred acquisition costs and operating	55		71		69
Interest	56		56		65
Expenses of consolidated VIEs	0		0		0
Inter-segment expenses	23	[2]	22	[2]	22	[3]
Total expenses	134		149		156
Income (loss) from continuing operations before income taxes	33		17		(133)
Identifiable assets per segment	645
Assets held for sale	0
Identifiable assets	645		873
Operating Segments [Member] | International And Structured Finance Insurance [Member]
Segment Reporting Information [Line Items]
Revenues	39	[1]	44	[1]	30
Net gains (losses) on financial instruments at fair value and foreign exchange	(7)		(14)		(8)
Net gains (losses) on extinguishment of debt	0		0
Revenues of consolidated VIEs	5		(23)		163
Inter-segment revenues	9	[2]	12	[2]	12
Total revenues	46		19		197
Losses and loss adjustment	(105)		123		367
Amortization of deferred acquisition costs and operating	12		9		14
Interest	124		107		113
Expenses of consolidated VIEs	9		24		55
Inter-segment expenses	27	[2]	38	[2]	39	[3]
Total expenses	67		301		588
Income (loss) from continuing operations before income taxes	(21)		(282)		(391)
Identifiable assets per segment	1,132
Assets held for sale	0
Identifiable assets	1,132		2,800
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Revenues	0	[1]	0	[1]	0
Net gains (losses) on financial instruments at fair value and foreign exchange	0		0		0
Net gains (losses) on extinguishment of debt	(1)		0
Revenues of consolidated VIEs	0		0		0
Inter-segment revenues	(93)	[2]	(106)	[2]	(106)
Total revenues	(94)		(106)		(106)
Losses and loss adjustment	0		0		0
Amortization of deferred acquisition costs and operating	1		0		0
Interest	(1)		0		0
Expenses of consolidated VIEs	0		0		0
Inter-segment expenses	(94)	[2]	(105)	[2]	(106)	[3]
Total expenses	(94)		(105)		(106)
Income (loss) from continuing operations before income taxes	0		(1)		$ 0
Identifiable assets per segment	(973)
Assets held for sale	0
Identifiable assets	$ (973)		$ (2,290)

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