Goodwill and Other Intangibles - Changes in the carrying value of goodwill (Details) - USD ($) $ in Millions			3 Months Ended		12 Months Ended
	Jul. 03, 2023	Dec. 06, 2021	Dec. 31, 2023	Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2021
Goodwill [Line Items]
Goodwill, beginning balance					$ 246	$ 176
Goodwill, impairment loss				$ (26)
Goodwill, ending balance			$ 305		305	246
Verikai, Inc.
Goodwill [Line Items]
Goodwill, impairment loss			$ (26)
Verikai, Inc.
Goodwill [Line Items]
Goodwill acquired during period		$ 70				$ 70
Crop Risk Services
Goodwill [Line Items]
Goodwill acquired during period	$ 85				$ 85