Statutory Information and Dividend Limitations - Combined Net Income and Capital and Surplus (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Statutory Accounting Practices [Line Items]
Statutory net income	$ 316.9	$ 383.9	$ (146.4)
Statutory capital and surplus	1,832.4	2,083.4
Subsidiaries \| Life and Health Companies
Statutory Accounting Practices [Line Items]
Statutory net income	130.4	(56.8)	4.0
Statutory capital and surplus	273.7	322.2
Subsidiaries \| Domestic \| Property and Casualty Companies
Statutory Accounting Practices [Line Items]
Statutory net income	186.5	440.7	(150.4)
Statutory capital and surplus	1,558.7	1,761.2
Subsidiaries \| Domestic \| Life and Health Companies
Statutory Accounting Practices [Line Items]
Statutory net income	16.5	17.1	(136.0)
Statutory capital and surplus	108.4	124.3
Subsidiaries \| Foreign \| Life and Health Companies
Statutory Accounting Practices [Line Items]
Statutory net income	113.9	(73.9)	$ 140.0
Statutory capital and surplus	$ 165.3	$ 197.9