Distribution Across Property Type and Geographic Region for Commercial Mortgage Loans (Detail) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 6,915	$ 7,032
% of total	100.00%	100.00%
Allowance for credit losses	$ (24)	$ (22)
Commercial mortgage loans, net	6,891	7,010
Commercial Mortgage Loan
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 6,915	$ 7,032
% of total	100.00%	100.00%
Allowance for credit losses	$ (24)	$ (22)
Commercial mortgage loans, net	6,891	7,010
South Atlantic | Commercial Mortgage Loan
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 1,788	$ 1,809
% of total	26.00%	26.00%
Pacific | Commercial Mortgage Loan
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 1,324	$ 1,340
% of total	19.00%	19.00%
Mountain | Commercial Mortgage Loan
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 1,013	$ 1,023
% of total	15.00%	15.00%
Middle Atlantic | Commercial Mortgage Loan
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 953	$ 988
% of total	14.00%	14.00%
West South Central | Commercial Mortgage Loan
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 572	$ 578
% of total	8.00%	8.00%
East North Central | Commercial Mortgage Loan
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 448	$ 454
% of total	6.00%	6.00%
West North Central | Commercial Mortgage Loan
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 419	$ 438
% of total	6.00%	6.00%
East South Central | Commercial Mortgage Loan
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 216	$ 218
% of total	3.00%	3.00%
New England | Commercial Mortgage Loan
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 182	$ 184
% of total	3.00%	3.00%
Retail
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 2,855	$ 2,916
% of total	42.00%	42.00%
Office
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 1,549	$ 1,579
% of total	22.00%	22.00%
Industrial
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 1,449	$ 1,456
% of total	21.00%	21.00%
Apartments
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 549	$ 561
% of total	8.00%	8.00%
Mixed Use
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 365	$ 371
% of total	5.00%	5.00%
Other
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 148	$ 149
% of total	2.00%	2.00%