Investments - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 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	93,487	$ 99,171
Limited Partnership Interests \| Variable interest Entity, not primary beneficiary
Schedule of Investments [Line Items]
Total Assets	$ 1,936	1,829
Finance and insurance \| Fixed maturity securities
Schedule of Investments [Line Items]
Percent of investment portfolio, greater than 10%	24.00%
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%	15.00%
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]
Write-offs		8
Office \| 31 to 60 Past due
Schedule of Investments [Line Items]
Commercial mortgage loans on nonaccrual status		$ 22
Office \| More than 90 days past due
Schedule of Investments [Line Items]
Commercial mortgage loans on nonaccrual status	$ 22

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