Other Policyholder Funds and Benefits Payable (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024	Dec. 31, 2023
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Other policyholder funds and benefits payable	$ 614	$ 613	$ 614
Universal Life
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Other policyholder funds and benefits payable	197	209	$ 206	$ 223
Policyholder Account Balance, Premium Received	9	9
Policyholder Account Balance, Policy Charge	14	18
Policyholder Account Balance, Surrender and Withdrawal	4	4
Policyholder Account Balance, Benefit Payment	6	6
Policyholder Account Balance, Interest Expense	$ 6	$ 5
Policyholder Account Balance, Weighted Average Crediting Rate	4.30%	4.30%
Policyholder Account Balance, Net Amount at Risk	$ 775	$ 852
Policyholder Account Balance, Cash Surrender Value	$ 196	207
Universal Life | Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0400 to 0499 | Minimum
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Policyholder Account Balance, Guaranteed Minimum Credit Rating	4.00%
Universal Life | Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0400 to 0499 | Maximum
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Policyholder Account Balance, Guaranteed Minimum Credit Rating	5.00%
Universal Life | Policyholder Account Balance, at Guaranteed Minimum Crediting Rate | Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0400 to 0499
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Other policyholder funds and benefits payable	$ 196	208
Short-Duration Insurance, Other
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Other policyholder funds and benefits payable	$ 417	$ 404