Investments - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021
Schedule of Investments [Line Items]
Percentage of investment portfolio by which no other industry group exceeded	10.00%
Percentage of stockholders' equity by which no single issuer of fixed maturity securities exceeded	10
Commercial mortgage loans on nonaccrual status	$ 0
Total Assets	86,442	$ 99,171
Commercial mortgage loans, amortized cost	7,032	6,856
Commercial mortgage-backed
Schedule of Investments [Line Items]
Commercial mortgage loans,Allowance for credit losses	0
Limited Partnerships \| Variable interest Entity, not primary beneficiary
Schedule of Investments [Line Items]
Total Assets	$ 2,230	1,829
Finance and insurance \| Fixed maturity securities
Schedule of Investments [Line Items]
Percent of investment portfolio, greater than 10%	27.00%
Utilities \| Fixed maturity securities
Schedule of Investments [Line Items]
Percent of investment portfolio, greater than 10%	13.00%
Consumer-non-cyclical \| Fixed maturity securities
Schedule of Investments [Line Items]
Percent of investment portfolio, greater than 10%	14.00%
Insurance [Member]
Schedule of Investments [Line Items]
Securities on deposit with various state government insurance departments	$ 42	45
Technology and Communications \| Fixed maturity securities
Schedule of Investments [Line Items]
Percent of investment portfolio, greater than 10%	11.00%
Office
Schedule of Investments [Line Items]
Commercial mortgage loans, amortized cost	$ 1,579	1,526
Write-offs		8
Office \| 31 to 60 Past due
Schedule of Investments [Line Items]
Commercial mortgage loans, amortized cost		$ 22

Concentration risk of greater than or equal to 10% of fixed maturity securities.

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