Catastrophe Reinsurance - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Liability for Catastrophe Claims [Line Items]
Catastrophic events classification by amount	$ 25,000,000
Ceded earned premiums	32,700,000	$ 42,700,000	$ 36,100,000
Incurred losses and LAE related to prior year (favorable) adverse development	159,800,000	(14,600,000)	106,700,000
Catastrophe
Liability for Catastrophe Claims [Line Items]
Catastrophe Losses and LAE	87,600,000	75,200,000	102,400,000
Incurred losses and LAE related to prior year (favorable) adverse development	(9,100,000)	(4,100,000)	(5,400,000)
Catastrophe | Life Insurance
Liability for Catastrophe Claims [Line Items]
Catastrophe Losses and LAE	3,000,000.0	3,300,000	12,900,000
Incurred losses and LAE related to prior year (favorable) adverse development	800,000	1,500,000	(100,000)
Catastrophe | Specialty Property & Casualty Insurance
Liability for Catastrophe Claims [Line Items]
Catastrophe Losses and LAE	32,200,000	23,600,000	16,000,000.0
Incurred losses and LAE related to prior year (favorable) adverse development	(2,300,000)	600,000	300,000
Catastrophe | Non-Core Operations
Liability for Catastrophe Claims [Line Items]
Catastrophe Losses and LAE	52,400,000	48,300,000	73,500,000
Incurred losses and LAE related to prior year (favorable) adverse development	$ (7,600,000)	$ (6,200,000)	$ (5,600,000)