Dispositions (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents	$ 3.1	$ 0.0	$ 0.0	$ 0.0
Disposal Group, Including Discontinued Operation, Liabilities	84.8	$ 0.0
Disposal Group, Including Discontinued Operation, Consideration	90.0
Reserve National Insurance Company | Disposal Group, Held-for-sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Not Discontinued Operation, Impairment	(4.5)
Disposal Group, Including Discontinued Operations, Debt Securities, Available-for-Sale, Amortized Cost	121.1
Disposal Group, Including Discontinued Operation, Debt Securities, Available-for-Sale	102.0
Disposal Group, Including Discontinued Operation, Other Short-Term Investments	0.4
Disposal Group, Including Discontinued Operation, Loans, Gross, Insurance Policy	0.7
Disposal Group, Including Discontinued Operation, Investments	103.1
Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents	3.1
Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net	3.3
Disposal Group, Including Discontinued Operation, Other Receivables	2.5
Disposal Group, Including Discontinued Operation, Deferred Policy Acquisition Cost	38.7
Disposal Group, Including Discontinued Operation, Goodwill	8.7
Disposal Group, Including Discontinued Operation, Income Tax Receivable	7.3
Disposal Group, Including Discontinued Operation, Deferred Tax Assets	3.6
Disposal Group, Including Discontinued Operation, Other Assets	2.5
Disposal Group, Including Discontinued Operation, Assets	172.8
Liability for Claims and Claims Adjustment Expense, Disability, Accident and Health	49.5
Disposal Group, Including Discontinued Operation, Unearned Premiums	10.5
Accrued Liabilities and Other Liabilities	24.8
Disposal Group, Including Discontinued Operation, Liabilities	84.8
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal	2.0
Disposal Group, Not Discontinued Operation, Gain (Loss) On Disposal, Net Of Tax	$ 1.6