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Reinsurance (Schedule of Trust Assets and Reinsurance Liabilities) (Details) - USD ($) $ in Millions		Jun. 30, 2026	Dec. 31, 2025	Jun. 30, 2025	Dec. 31, 2024
Reinsurance [Line Items]
Restricted cash and cash equivalents		$ 490.7	$ 477.9	$ 493.8	$ 501.3
Debt Securities, Available-for-sale, Restricted		116.6	106.2
Trust Assets [Member]
Reinsurance [Line Items]
Restricted cash and cash equivalents		0.8	0.7
Debt Securities, Available-for-sale, Restricted		116.6	106.2
Unearned Premium [Member]
Reinsurance [Line Items]
Accounts payable and accrued liabilities		78.3	74.0
Claims Reserve [Member]
Reinsurance [Line Items]
Accounts payable and accrued liabilities	[1]	$ 5.9	$ 5.9
[1] The claims reserve represents our liability for incurred-but-not-reported claims and is estimated based on historical claims experience.

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Summary Of Significant Accounting Policies [Line Items]

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Sum of the carrying values as of the balance sheet date of obligations incurred through that date, including liabilities incurred and payable to vendors for goods and services received, taxes, interest, rent and utilities, compensation costs, payroll taxes and fringe benefits (other than pension and postretirement obligations), contractual rights and obligations, and statutory obligations.

+ References

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-Topic 942
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Amount of restricted investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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-Topic 954
-SubTopic 210
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Amount of cash and cash equivalent restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposit with financial institution, and account with general characteristic of demand deposit. Cash equivalent includes, but is not limited to, short-term, highly liquid investment that is both readily convertible to known amount of cash and so near maturity that it presents insignificant risk of change in value because of change in interest rate.

+ References

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