Derivative Instruments (Effect Of Derivative Instruments On Consolidated Statements Of Operations) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Net gain/(loss) recognized in income	$ 21	$ (53)	$ (85)
Credit Default Swap [Member] | Unrealized Gains Losses On Insured Derivatives [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	0	7	25
Credit Default Swap [Member] | Realized Gains Losses And Other Settlements On Insured Derivatives [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	0	(1)	(10)
Interest Rate Swap [Member] | Net gains (losses) on financial instruments at fair value and foreign exchange [Member
Derivative [Line Items]
Net gain/(loss) recognized in income	18	(42)	(66)
Currency Swaps Vie [Member] | Net gains (losses) on financial instruments at fair value and foreign exchange-VIE [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	3	(2)	(8)
All Other [Member] | Net gains (losses) on financial instruments at fair value and foreign exchange [Member
Derivative [Line Items]
Net gain/(loss) recognized in income	$ 0	$ (15)	$ (26)