Derivative Instruments (Total Fair Value Of Company's Derivative Assets And Liabilities By Instrument And Balance Sheet Location, Before Counterparty Netting) (Detail) - Not Designated as Hedging Instrument [Member] - Derivative Instrument [Member] - USD ($) $ in Millions		Sep. 30, 2022	Dec. 31, 2021
Derivative [Line Items]
Derivative notional amount		$ 1,958	$ 2,144
Derivative Assets, Not designated, Fair Value	[1]	0	10
Derivative Liabilities, Not designated, Fair Value	[1]	(55)	(140)
Insured swaps [Member]
Derivative [Line Items]
Derivative notional amount		1,367	1,489
Insured swaps [Member] | Other assets [Member]
Derivative [Line Items]
Derivative Assets, Not designated, Fair Value	[1]	0	0
Insured swaps [Member] | Derivative liabilities [Member]
Derivative [Line Items]
Derivative Liabilities, Not designated, Fair Value	[1]	0	(1)
Interest rate swaps [Member]
Derivative [Line Items]
Derivative notional amount		375	399
Interest rate swaps [Member] | Other assets [Member]
Derivative [Line Items]
Derivative Assets, Not designated, Fair Value	[1]	0	1
Interest rate swaps [Member] | Derivative liabilities [Member]
Derivative [Line Items]
Derivative Liabilities, Not designated, Fair Value	[1]	(49)	(130)
Interest rate swaps-embedded [Member]
Derivative [Line Items]
Derivative notional amount		178	206
Interest rate swaps-embedded [Member] | Medium-term notes [Member]
Derivative [Line Items]
Derivative Assets, Not designated, Fair Value	[1]	0	0
Derivative Liabilities, Not designated, Fair Value	[1]	(1)	(9)
Currency swaps-VIE [Member]
Derivative [Line Items]
Derivative notional amount		38	50
Currency swaps-VIE [Member] | Other assets-VIE [Member]
Derivative [Line Items]
Derivative Assets, Not designated, Fair Value	[1]	0	9
Currency swaps-VIE [Member] | Derivative liabilities-VIE [Member]
Derivative [Line Items]
Derivative Liabilities, Not designated, Fair Value	[1]	$ (5)	$ 0

[1] In accordance with the accounting guidance for derivative instruments and hedging activities, the balance sheet location of the Company’s embedded derivative instruments is determined by the location of the related host contract.