Investments - Investments - Loan-to-Value and Debt Service Coverage Ratio by Origination Year (Details) $ in Millions	Sep. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Schedule of Investments [Line Items]
Current Weighted Average Loan to Value Ratio of Commercial Mortgage Loan	53.00%
Original Weighted Average Loan to Value Ratio of Commercial Mortgage loan	59.00%
Commercial Loan [Member]
Schedule of Investments [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 6,062	$ 6,036
Avg. Debt-Service Coverage Ratio	2.63	2.59
Commercial Loan [Member] | LTV Greater than 80 Percent
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	1.90	1.40
Commercial Loan [Member] | 65% - 80%
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	2.10	1.91
Commercial Loan [Member] | Less than 65%
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	2.70	2.65
Amortized Cost [Member] | Commercial Loan [Member]
Schedule of Investments [Line Items]
Mortgage loans originated in current year	$ 260	$ 855
Mortgage loans originated in year before latest fiscal year	913	1,534
Mortgage loans originated two years before latest fiscal year	1,622	706
Mortgage loans originated three years before latest fiscal year	643	780
Mortgage loans originated four years before latest fiscal year	779	545
Mortgage loans originated five or more years before latest fiscal year	1,845	1,616
Financing Receivable, before Allowance for Credit Loss	6,062	6,036
Amortized Cost [Member] | Commercial Loan [Member] | LTV Greater than 80 Percent
Schedule of Investments [Line Items]
Mortgage loans originated in current year	0	0
Mortgage loans originated in year before latest fiscal year	0	0
Mortgage loans originated two years before latest fiscal year	0	0
Mortgage loans originated three years before latest fiscal year	0	0
Mortgage loans originated four years before latest fiscal year	0	0
Mortgage loans originated five or more years before latest fiscal year	53	23
Financing Receivable, before Allowance for Credit Loss	53	23
Amortized Cost [Member] | Commercial Loan [Member] | 65% - 80%
Schedule of Investments [Line Items]
Mortgage loans originated in current year	0	16
Mortgage loans originated in year before latest fiscal year	24	59
Mortgage loans originated two years before latest fiscal year	177	43
Mortgage loans originated three years before latest fiscal year	89	100
Mortgage loans originated four years before latest fiscal year	99	108
Mortgage loans originated five or more years before latest fiscal year	224	117
Financing Receivable, before Allowance for Credit Loss	613	443
Amortized Cost [Member] | Commercial Loan [Member] | Less than 65%
Schedule of Investments [Line Items]
Mortgage loans originated in current year	260	839
Mortgage loans originated in year before latest fiscal year	889	1,475
Mortgage loans originated two years before latest fiscal year	1,445	663
Mortgage loans originated three years before latest fiscal year	554	680
Mortgage loans originated four years before latest fiscal year	680	437
Mortgage loans originated five or more years before latest fiscal year	1,568	1,476
Financing Receivable, before Allowance for Credit Loss	$ 5,396	$ 5,570
Originated in Current Fiscal Year | Commercial Loan [Member]
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	1.59	2.42
Originated in Current Fiscal Year | Commercial Loan [Member] | LTV Greater than 80 Percent
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	0	0
Originated in Current Fiscal Year | Commercial Loan [Member] | 65% - 80%
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	0	2.02
Originated in Current Fiscal Year | Commercial Loan [Member] | Less than 65%
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	1.59	2.43
Originated in Fiscal Year Before Latest Fiscal Year | Commercial Loan [Member]
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	2.64	2.78
Originated in Fiscal Year Before Latest Fiscal Year | Commercial Loan [Member] | LTV Greater than 80 Percent
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	0	0
Originated in Fiscal Year Before Latest Fiscal Year | Commercial Loan [Member] | 65% - 80%
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	2.37	2.61
Originated in Fiscal Year Before Latest Fiscal Year | Commercial Loan [Member] | Less than 65%
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	2.65	2.79
Originated Two Years Before Latest Fiscal Year | Commercial Loan [Member]
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	2.78	3.01
Originated Two Years Before Latest Fiscal Year | Commercial Loan [Member] | LTV Greater than 80 Percent
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	0	0
Originated Two Years Before Latest Fiscal Year | Commercial Loan [Member] | 65% - 80%
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	2.46	2.78
Originated Two Years Before Latest Fiscal Year | Commercial Loan [Member] | Less than 65%
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	2.82	3.02
Originated Three Years Before Latest Fiscal Year | Commercial Loan [Member]
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	3.08	2.66
Originated Three Years Before Latest Fiscal Year | Commercial Loan [Member] | LTV Greater than 80 Percent
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	0	0
Originated Three Years Before Latest Fiscal Year | Commercial Loan [Member] | 65% - 80%
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	3.45	1.95
Originated Three Years Before Latest Fiscal Year | Commercial Loan [Member] | Less than 65%
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	3.02	2.77
Originated Four Years Before Latest Fiscal Year | Commercial Loan [Member]
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	2.78	1.99
Originated Four Years Before Latest Fiscal Year | Commercial Loan [Member] | LTV Greater than 80 Percent
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	0	0
Originated Four Years Before Latest Fiscal Year | Commercial Loan [Member] | 65% - 80%
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	2.01	1.11
Originated Four Years Before Latest Fiscal Year | Commercial Loan [Member] | Less than 65%
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	2.89	2.21
Originated Five or More Years Before Latest Fiscal Year | Commercial Loan [Member]
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	2.42	2.48
Originated Five or More Years Before Latest Fiscal Year | Commercial Loan [Member] | LTV Greater than 80 Percent
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	1.90	1.40
Originated Five or More Years Before Latest Fiscal Year | Commercial Loan [Member] | 65% - 80%
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	1.31	1.91
Originated Five or More Years Before Latest Fiscal Year | Commercial Loan [Member] | Less than 65%
Schedule of Investments [Line Items]
Avg. Debt-Service Coverage Ratio	2.59	2.54