Dispositions - Assets and Liabilities Included in Disposition (Details) - Disposal Group, Disposed of by Sale, Not Discontinued Operations - Reserve National Insurance Company - USD ($) $ in Millions	Dec. 31, 2023	Dec. 01, 2022
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Fixed Maturities at Fair Value (Amortized Cost: $43.3)		$ 36.7
Fixed maturities, amortized cost	$ 43.3
Short-term Investments at Cost which Approximates Fair Value		0.7
Loans to Policyholders		0.7
Total Investments		38.1
Cash		81.0
Receivables from Policyholders		2.6
Other Receivables		1.6
Deferred Policy Acquisition Costs		38.7
Goodwill		0.3
Other Assets		3.1
Investment in Subsidiaries		0.2
Total Assets		165.6
Health Insurance Reserves		48.2
Unearned Premiums		10.8
Deferred Income Tax Liabilities		1.8
Accrued Expenses and Other Liabilities		13.8
Total Liabilities		$ 74.6