Reinsurance - Narrative (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($)	Oct. 01, 2023 agreement
Ceded Credit Risk [Line Items]
Number of reinsurance recoverable agreements | agreement						2
Investments	$ 136,102		$ 136,102		$ 129,918
Fortitude Re
Ceded Credit Risk [Line Items]
Deposits assets	8,400		8,400		8,100
Investments	9,100		9,100		9,300
Fixed Annuities | Fortitude Re
Ceded Credit Risk [Line Items]
Reinsurance recoverables	10,600		10,600		10,600
Reinsurance recoverables on unpaid losses	2,500		2,500		2,600
Reinsurance recoverable amortization	23	$ 23	69	$ 67
Deposits assets	$ 2,500		$ 2,500		$ 3,000