Investments - Schedule of Residential Mortgage Loans with Credit Quality Indicators, Performing or Nonperforming (Details) - USD ($) $ in Millions	Sep. 30, 2025	Jun. 30, 2025	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Dec. 31, 2023
Schedule of Investments [Line Items]
Allowance for expected loan loss	$ (77)	$ (75)	$ (70)	$ (69)	$ (64)	$ (66)
Total CMLs, net of valuation allowance	7,391		5,926
Residential Mortgage
Schedule of Investments [Line Items]
Amortized Cost	$ 4,165		$ 3,274
% of Total	100.00%		100.00%
Allowance for expected loan loss	$ (58)	$ (58)	$ (53)	$ (51)	$ (50)	$ (54)
Total CMLs, net of valuation allowance	4,107		3,221
Performing \| Residential Mortgage
Schedule of Investments [Line Items]
Amortized Cost	$ 4,093		$ 3,188
% of Total	98.00%		97.00%
Non-performing \| Residential Mortgage
Schedule of Investments [Line Items]
Amortized Cost	$ 72		$ 86
% of Total	2.00%		3.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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