Investments - Changes in Allowance for Credit Losses on Mortgage Loans on Real Estate (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance as of beginning-of-year	$ 114,000,000
Additions (reductions) from provision for credit loss expense	0	$ 4,000,000
Balance as of end-of-year	115,000,000
Accrued interest receivable excluded from credit losses	69,000,000	52,000,000
Mortgage loans on real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance as of beginning-of-year	114,000,000	99,000,000
Additions (reductions) from provision for credit loss expense	1,000,000	4,000,000
Additions from purchases of PCD mortgage loans on real estate	0	0
Balance as of end-of-year	115,000,000	103,000,000
Credit loss expense (reversal)	1,000,000	0
Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance as of beginning-of-year	86,000,000
Balance as of end-of-year	84,000,000
Commercial | Mortgage loans on real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance as of beginning-of-year	86,000,000	84,000,000
Additions (reductions) from provision for credit loss expense	(2,000,000)	(1,000,000)
Additions from purchases of PCD mortgage loans on real estate	0	0
Balance as of end-of-year	84,000,000	83,000,000
Residential
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance as of beginning-of-year	28,000,000
Balance as of end-of-year	31,000,000
Residential | Mortgage loans on real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance as of beginning-of-year	28,000,000	15,000,000
Additions (reductions) from provision for credit loss expense	3,000,000	5,000,000
Additions from purchases of PCD mortgage loans on real estate	0	0
Balance as of end-of-year	$ 31,000,000	$ 20,000,000