Investments - Schedule of Investment in CMLs by Loan to Value and Debt Service Coverage Ratios (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Credit Quality Indicator Prior Year [Abstract]
Loans under development, amortized cost		$ 22
Loans under development, fair value		22
Commercial Mortgages
Schedule of Investments [Line Items]
Loans	$ 2,590	$ 2,528
% of Total	100.00%	100.00%
Credit Quality Indicator Current Year [Abstract]
2024	$ 140	$ 213
2023	221	288
2022	289	1,256
2021	1,253	512
2020	469	0
Prior	218	259
Total	2,590	2,528
Credit Quality Indicator Prior Year [Abstract]
2023	140	213
2022	221	288
2021	289	1,256
2020	1,253	512
2019	469	0
Prior	218	259
Total	2,590	2,528
Commercial Mortgages | Fair Value
Schedule of Investments [Line Items]
Loans	$ 2,342	$ 2,231
% of Total	100.00%	100.00%
Credit Quality Indicator Current Year [Abstract]
Total	$ 2,342	$ 2,231
Credit Quality Indicator Prior Year [Abstract]
Total	2,342	2,231
Commercial Mortgages | Less than 50.00%
Schedule of Investments [Line Items]
Loans	$ 516	$ 533
% of Total	20.00%	21.00%
Credit Quality Indicator Current Year [Abstract]
2024	$ 58	$ 85
2023	93	17
2022	18	77
2021	74	232
2020	189	0
Prior	84	122
Total	516	533
Credit Quality Indicator Prior Year [Abstract]
2023	58	85
2022	93	17
2021	18	77
2020	74	232
2019	189	0
Prior	84	122
Total	516	533
Commercial Mortgages | Less than 50.00% | Fair Value
Schedule of Investments [Line Items]
Loans	$ 501	$ 510
% of Total	21.00%	23.00%
Credit Quality Indicator Current Year [Abstract]
Total	$ 501	$ 510
Credit Quality Indicator Prior Year [Abstract]
Total	501	510
Commercial Mortgages | 50.00% to 59.99%
Schedule of Investments [Line Items]
Loans	$ 820	$ 764
% of Total	31.00%	30.00%
Credit Quality Indicator Current Year [Abstract]
2024	$ 59	$ 53
2023	53	149
2022	149	267
2021	267	158
2020	158	0
Prior	134	137
Total	820	764
Credit Quality Indicator Prior Year [Abstract]
2023	59	53
2022	53	149
2021	149	267
2020	267	158
2019	158	0
Prior	134	137
Total	820	764
Commercial Mortgages | 50.00% to 59.99% | Fair Value
Schedule of Investments [Line Items]
Loans	$ 752	$ 679
% of Total	32.00%	30.00%
Credit Quality Indicator Current Year [Abstract]
Total	$ 752	$ 679
Credit Quality Indicator Prior Year [Abstract]
Total	752	679
Commercial Mortgages | 60.00% to 74.99%
Schedule of Investments [Line Items]
Loans	$ 1,239	$ 1,216
% of Total	48.00%	48.00%
Credit Quality Indicator Current Year [Abstract]
2024	$ 23	$ 69
2023	69	113
2022	113	912
2021	912	122
2020	122	0
Prior	0	0
Total	1,239	1,216
Credit Quality Indicator Prior Year [Abstract]
2023	23	69
2022	69	113
2021	113	912
2020	912	122
2019	122	0
Prior	0	0
Total	1,239	1,216
Commercial Mortgages | 60.00% to 74.99% | Fair Value
Schedule of Investments [Line Items]
Loans	$ 1,074	$ 1,028
% of Total	46.00%	46.00%
Credit Quality Indicator Current Year [Abstract]
Total	$ 1,074	$ 1,028
Credit Quality Indicator Prior Year [Abstract]
Total	1,074	1,028
Commercial Mortgages | 75.00% to 84.99%
Schedule of Investments [Line Items]
Loans	$ 15	$ 15
% of Total	1.00%	1.00%
Credit Quality Indicator Current Year [Abstract]
2024	$ 0	$ 6
2023	6	9
2022	9	0
2021	0	0
2020	0	0
Prior	0	0
Total	15	15
Credit Quality Indicator Prior Year [Abstract]
2023	0	6
2022	6	9
2021	9	0
2020	0	0
2019	0	0
Prior	0	0
Total	15	15
Commercial Mortgages | 75.00% to 84.99% | Fair Value
Schedule of Investments [Line Items]
Loans	$ 15	$ 14
% of Total	1.00%	1.00%
Credit Quality Indicator Current Year [Abstract]
Total	$ 15	$ 14
Credit Quality Indicator Prior Year [Abstract]
Total	15	14
Greater than 1.25 | Commercial Mortgages
Schedule of Investments [Line Items]
Loans	2,430	2,443
Credit Quality Indicator Current Year [Abstract]
2024	72	154
2023	161	276
2022	278	1,256
2021	1,241	512
2020	469	0
Prior	209	245
Total	2,430	2,443
Credit Quality Indicator Prior Year [Abstract]
2023	72	154
2022	161	276
2021	278	1,256
2020	1,241	512
2019	469	0
Prior	209	245
Total	2,430	2,443
Greater than 1.25 | Commercial Mortgages | Less than 50.00%
Schedule of Investments [Line Items]
Loans	499	519
Credit Quality Indicator Current Year [Abstract]
Total	499	519
Credit Quality Indicator Prior Year [Abstract]
Total	499	519
Greater than 1.25 | Commercial Mortgages | 50.00% to 59.99%
Schedule of Investments [Line Items]
Loans	749	764
Credit Quality Indicator Current Year [Abstract]
Total	749	764
Credit Quality Indicator Prior Year [Abstract]
Total	749	764
Greater than 1.25 | Commercial Mortgages | 60.00% to 74.99%
Schedule of Investments [Line Items]
Loans	1,182	1,160
Credit Quality Indicator Current Year [Abstract]
Total	1,182	1,160
Credit Quality Indicator Prior Year [Abstract]
Total	1,182	1,160
Greater than 1.25 | Commercial Mortgages | 75.00% to 84.99%
Schedule of Investments [Line Items]
Loans	0	0
Credit Quality Indicator Current Year [Abstract]
Total	0	0
Credit Quality Indicator Prior Year [Abstract]
Total	0	0
Greater than 1.00 but less than 1.25 | Commercial Mortgages
Schedule of Investments [Line Items]
Loans	130	66
Credit Quality Indicator Current Year [Abstract]
2024	67	59
2023	60	3
2022	3	0
2021	0	0
2020	0	0
Prior	0	4
Total	130	66
Credit Quality Indicator Prior Year [Abstract]
2023	67	59
2022	60	3
2021	3	0
2020	0	0
2019	0	0
Prior	0	4
Total	130	66
Greater than 1.00 but less than 1.25 | Commercial Mortgages | Less than 50.00%
Schedule of Investments [Line Items]
Loans	8	4
Credit Quality Indicator Current Year [Abstract]
Total	8	4
Credit Quality Indicator Prior Year [Abstract]
Total	8	4
Greater than 1.00 but less than 1.25 | Commercial Mortgages | 50.00% to 59.99%
Schedule of Investments [Line Items]
Loans	59	0
Credit Quality Indicator Current Year [Abstract]
Total	59	0
Credit Quality Indicator Prior Year [Abstract]
Total	59	0
Greater than 1.00 but less than 1.25 | Commercial Mortgages | 60.00% to 74.99%
Schedule of Investments [Line Items]
Loans	57	56
Credit Quality Indicator Current Year [Abstract]
Total	57	56
Credit Quality Indicator Prior Year [Abstract]
Total	57	56
Greater than 1.00 but less than 1.25 | Commercial Mortgages | 75.00% to 84.99%
Schedule of Investments [Line Items]
Loans	6	6
Credit Quality Indicator Current Year [Abstract]
Total	6	6
Credit Quality Indicator Prior Year [Abstract]
Total	6	6
Less than 1.00 | Commercial Mortgages
Schedule of Investments [Line Items]
Loans	30	19
Credit Quality Indicator Current Year [Abstract]
2024	1	0
2023	0	9
2022	8	0
2021	12	0
2020	0	0
Prior	9	10
Total	30	19
Credit Quality Indicator Prior Year [Abstract]
2023	1	0
2022	0	9
2021	8	0
2020	12	0
2019	0	0
Prior	9	10
Total	30	19
Less than 1.00 | Commercial Mortgages | Less than 50.00%
Schedule of Investments [Line Items]
Loans	9	10
Credit Quality Indicator Current Year [Abstract]
Total	9	10
Credit Quality Indicator Prior Year [Abstract]
Total	9	10
Less than 1.00 | Commercial Mortgages | 50.00% to 59.99%
Schedule of Investments [Line Items]
Loans	12	0
Credit Quality Indicator Current Year [Abstract]
Total	12	0
Credit Quality Indicator Prior Year [Abstract]
Total	12	0
Less than 1.00 | Commercial Mortgages | 60.00% to 74.99%
Schedule of Investments [Line Items]
Loans	0	0
Credit Quality Indicator Current Year [Abstract]
Total	0	0
Credit Quality Indicator Prior Year [Abstract]
Total	0	0
Less than 1.00 | Commercial Mortgages | 75.00% to 84.99%
Schedule of Investments [Line Items]
Loans	9	9
Credit Quality Indicator Current Year [Abstract]
Total	9	9
Credit Quality Indicator Prior Year [Abstract]
Total	$ 9	$ 9