Investments - Schedule of Bank Loans Amortized Cost by Credit Rating and Year of Origination (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Debt Securities, Available-for-Sale [Line Items]
Amortized cost, net	$ 831	$ 784
Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	400	211
Allowance	(17)	(10)
Amortized cost, net	383	201
NAIC 1 / A | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	199	45
NAIC 2 / BBB | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	50	6
NAIC 3 / BB | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	25	27
NAIC 4 / B | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	108	122
NAIC 5-6 / CCC and below | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	18	$ 11
2020 and prior | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	1
2020 and prior | NAIC 1 / A | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	0
2020 and prior | NAIC 2 / BBB | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	0
2020 and prior | NAIC 3 / BB | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	0
2020 and prior | NAIC 4 / B | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	1
2020 and prior | NAIC 5-6 / CCC and below | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	0
2021 | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	2
2021 | NAIC 1 / A | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	0
2021 | NAIC 2 / BBB | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	0
2021 | NAIC 3 / BB | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	0
2021 | NAIC 4 / B | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	2
2021 | NAIC 5-6 / CCC and below | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	0
2022 | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	2
2022 | NAIC 1 / A | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	0
2022 | NAIC 2 / BBB | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	0
2022 | NAIC 3 / BB | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	1
2022 | NAIC 4 / B | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	0
2022 | NAIC 5-6 / CCC and below | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	1
2023 | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	38
2023 | NAIC 1 / A | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	0
2023 | NAIC 2 / BBB | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	0
2023 | NAIC 3 / BB | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	2
2023 | NAIC 4 / B | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	28
2023 | NAIC 5-6 / CCC and below | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	8
2024 | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	81
2024 | NAIC 1 / A | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	44
2024 | NAIC 2 / BBB | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	1
2024 | NAIC 3 / BB | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	8
2024 | NAIC 4 / B | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	27
2024 | NAIC 5-6 / CCC and below | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	1
2025 | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	276
2025 | NAIC 1 / A | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	155
2025 | NAIC 2 / BBB | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	49
2025 | NAIC 3 / BB | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	14
2025 | NAIC 4 / B | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	50
2025 | NAIC 5-6 / CCC and below | Bank loans, net
Debt Securities, Available-for-Sale [Line Items]
Amortized cost before allowance	$ 8