Investments - Summary of the Credit Risk Profile of the Commercial Mortgage Loan Portfolio (Details) - Real Estate Loan - Commercial Portfolio Segment $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Schedule of Investments [Line Items]
Carrying value, after allowance for credit loss	$ 1,617	$ 1,614
Weighted Average
Schedule of Investments [Line Items]
Average Debt Service Coverage Ratio	1.97	1.89
Average Loan-to-Value Ratio	62.00%	60.00%
Below 60%
Schedule of Investments [Line Items]
Carrying value, after allowance for credit loss	$ 909	$ 901
Below 60% | Weighted Average
Schedule of Investments [Line Items]
Average Debt Service Coverage Ratio	2.18	2.12
60% to 79%
Schedule of Investments [Line Items]
Carrying value, after allowance for credit loss	$ 542	$ 564
60% to 79% | Weighted Average
Schedule of Investments [Line Items]
Average Debt Service Coverage Ratio	1.80	1.73
80% to 100%
Schedule of Investments [Line Items]
Carrying value, after allowance for credit loss	$ 166	$ 149
80% to 100% | Weighted Average
Schedule of Investments [Line Items]
Average Debt Service Coverage Ratio	1.48	1.17