Accumulated Other Comprehensive Income (Changes In The Components Of AOCI) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Beginning balance	$ (156)	$ (19)	$ (128)
Other comprehensive income (loss) before reclassification	114		101	[1]
Amounts reclassified from AOCI	40		8
Total other comprehensive income (loss)	154	30	109
Ending balance	(2)	(156)	(19)
ASU 2016-01
ASU transition adjustment		(164)
ASU 2018-02
ASU transition adjustment		(3)
Unrealized gains (losses) on AFS, net [Member]
Beginning balance	(39)	(10)	6
Other comprehensive income (loss) before reclassification	139		(24)
Amounts reclassified from AOCI	12		8
Total other comprehensive income (loss)	151	(24)	(16)
Ending balance	112	(39)	(10)
Unrealized gains (losses) on AFS, net [Member] | ASU 2016-01
ASU transition adjustment		(2)
Unrealized gains (losses) on AFS, net [Member] | ASU 2018-02
ASU transition adjustment		(3)
Foreign currency translation, net [Member]
Beginning balance	(7)	(9)	(134)
Other comprehensive income (loss) before reclassification	0		125
Total other comprehensive income (loss)	0	2	125
Ending balance	(7)	(7)	$ (9)
Instrument-specific credit risk of liabilities measured at fair value, net [Member]
Beginning balance	(110)
Other comprehensive income (loss) before reclassification	(25)
Amounts reclassified from AOCI	28
Total other comprehensive income (loss)	3	52
Ending balance	$ (107)	(110)
Instrument-specific credit risk of liabilities measured at fair value, net [Member] | ASU 2016-01
ASU transition adjustment		$ (162)

[1] (1) Includes items included in the Company’s loss calculation to adjust the carrying value of MBIA UK to its fair value less costs to sell for the year ended December 31, 2016. The sale was completed in January of 2017 and as such, these amounts included in AOCI were reversed and included in the Sale Transaction.