Investments (Summary of Allowance for Credit Losses on AFS Investments) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Ending balance	$ 0
Accounting Standards Update 2016-13 [Member]
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Beginning Balance	0
Additions not previously recorded	3
Additions arising from PCD Assets	0
Reductions from Securities Sold	0
Reductions – Intent to sell or MLTN	3
Change in Allowance Previously Recorded	0
Write- Offs	0
Recoveries	0
Ending balance	0
Corporate Obligations [Member]
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Ending balance	0
Corporate Obligations [Member] | Accounting Standards Update 2016-13 [Member]
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Beginning Balance	0
Additions not previously recorded	3
Additions arising from PCD Assets	0
Reductions from Securities Sold	0
Reductions – Intent to sell or MLTN	3
Change in Allowance Previously Recorded	0
Write- Offs	0
Recoveries	0
Ending balance	$ 0