Property and Casualty Insurance Reserves - Narrative (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred Losses and LAE Related to Prior Years	$ 22.5	$ (107.9)
Personal Automobile
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred Losses and LAE Related to Prior Years	31.6	(97.0)
Personal Automobile
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred Losses and LAE Related to Prior Years	(1.9)	(4.9)
Homeowners
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred Losses and LAE Related to Prior Years	6.1	4.3
Other Personal Lines
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred Losses and LAE Related to Prior Years	(5.8)	(2.0)
Commercial Automobile
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred Losses and LAE Related to Prior Years	$ (7.5)	$ (8.3)