Financing Receivables - Credit Quality Information - Syndicated Loans (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Financing receivables - credit quality information
Loan write-offs	$ 2,000,000	$ 1,000,000
Commercial Loans
Financing receivables - credit quality information
Loan write-offs	1,000,000	$ 1,000,000
Commercial Loans | Syndicated loans
Financing receivables - credit quality information
Recorded investment	138,000,000		$ 145,000,000
Loan write-offs	0
Amortized cost basis by year of origination and loan-to-value ratio
Year 1	17,000,000		42,000,000
Year 2	36,000,000		9,000,000
Year 3	3,000,000		44,000,000
Year 4	37,000,000		11,000,000
Year 5	9,000,000		25,000,000
Prior	36,000,000		14,000,000
Total	138,000,000		145,000,000
Commercial Loans | Syndicated loans | Risk 5
Financing receivables - credit quality information
Recorded investment	0		1,000,000
Amortized cost basis by year of origination and loan-to-value ratio
Year 1	0		0
Year 2	0		1,000,000
Year 3	0		0
Year 4	0		0
Year 5	0		0
Prior	0		0
Total	0		1,000,000
Commercial Loans | Syndicated loans | Risk 4
Financing receivables - credit quality information
Recorded investment	3,000,000		3,000,000
Amortized cost basis by year of origination and loan-to-value ratio
Year 1	0		0
Year 2	0		0
Year 3	0		0
Year 4	0		1,000,000
Year 5	1,000,000		2,000,000
Prior	2,000,000		0
Total	3,000,000		3,000,000
Commercial Loans | Syndicated loans | Risk 3
Financing receivables - credit quality information
Recorded investment	26,000,000		28,000,000
Amortized cost basis by year of origination and loan-to-value ratio
Year 1	0		2,000,000
Year 2	2,000,000		0
Year 3	0		12,000,000
Year 4	12,000,000		2,000,000
Year 5	2,000,000		2,000,000
Prior	10,000,000		10,000,000
Total	26,000,000		28,000,000
Commercial Loans | Syndicated loans | Risk 2
Financing receivables - credit quality information
Recorded investment	61,000,000		64,000,000
Amortized cost basis by year of origination and loan-to-value ratio
Year 1	12,000,000		26,000,000
Year 2	20,000,000		3,000,000
Year 3	1,000,000		17,000,000
Year 4	13,000,000		5,000,000
Year 5	3,000,000		11,000,000
Prior	12,000,000		2,000,000
Total	61,000,000		64,000,000
Commercial Loans | Syndicated loans | Risk 1
Financing receivables - credit quality information
Recorded investment	48,000,000		49,000,000
Amortized cost basis by year of origination and loan-to-value ratio
Year 1	5,000,000		14,000,000
Year 2	14,000,000		5,000,000
Year 3	2,000,000		15,000,000
Year 4	12,000,000		3,000,000
Year 5	3,000,000		10,000,000
Prior	12,000,000		2,000,000
Total	48,000,000		49,000,000
Commercial Loans | Syndicated loans | Past due
Financing receivables - credit quality information
Recorded investment	0		0
Amortized cost basis by year of origination and loan-to-value ratio
Total	$ 0		$ 0