Goodwill and Other Intangibles - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 305,000,000		$ 305,000,000		$ 246,000,000
Changes in the goodwill			59,000,000
Goodwill impairment loss	26,000,000
Amortizable intangible assets related to property and casualty insurance acquisitions	217,000,000		217,000,000		108,000,000
Accumulated amortization	35,000,000		35,000,000		$ 24,000,000
Amortization of intangible assets	$ 5,000,000	$ 2,000,000	$ 11,000,000	$ 7,000,000