Distribution Across Property Type and Geographic Region for Commercial Mortgage Loans (Detail) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 7,088	$ 6,856
% of total	100.00%	100.00%
Allowance for credit losses	$ (23)	$ (26)
Commercial mortgage loans, net	7,065	6,830
Commercial Mortgage Loan
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 7,088	$ 6,856
% of total	100.00%	100.00%
Allowance for credit losses	$ (23)	$ (26)
Commercial mortgage loans, net	7,065	6,830
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	$ 1,816	$ 1,770
% 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	$ 1,391	$ 1,360
% of total	20.00%	20.00%
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	$ 990	$ 964
% of total	14.00%	14.00%
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	$ 967	$ 892
% of total	14.00%	13.00%
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	$ 469	$ 465
% of total	6.00%	7.00%
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	$ 462	$ 461
% of total	6.00%	7.00%
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	$ 556	$ 483
% of total	8.00%	7.00%
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	$ 227	$ 224
% 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	$ 210	$ 237
% 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	$ 2,901	$ 2,774
% of total	41.00%	40.00%
Industrial
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 1,532	$ 1,420
% of total	22.00%	21.00%
Office
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 1,512	$ 1,526
% of total	21.00%	22.00%
Apartments
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 578	$ 585
% of total	8.00%	9.00%
Mixed Use
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Commercial mortgage loans, amortized cost	$ 350	$ 330
% 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	$ 215	$ 221
% of total	3.00%	3.00%