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Investment Income and Gains and Losses (Schedule of Net Realized and Unrealized Gains (Losses) on Investments Including Impairments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Gain (Loss) on Investments [Line Items]
Net realized and unrealized investment losses	$ (46.4)	$ (76.2)	$ (32.3)
Net realized and unrealized investment losses	(46.0)	(75.8)	(32.5)
Fixed Maturities [Member]
Gain (Loss) on Investments [Line Items]
Net realized and unrealized investment losses	(61.8)	(89.6)	(20.2)
Mortgage Loans on Real Estate [Member]
Gain (Loss) on Investments [Line Items]
Net realized and unrealized investment losses	(2.5)	(0.5)	(6.9)
Equity Securities [Member]
Gain (Loss) on Investments [Line Items]
Net realized and unrealized investment losses	19.0	14.2	(5.6)
Other Investments [Member]
Gain (Loss) on Investments [Line Items]
Net realized and unrealized investment losses	$ (0.7)	$ 0.1	$ 0.2

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Gain (loss) on investments from continuing operations.

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Amount of realized and unrealized gain (loss) on investment.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
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-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 230
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+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(9)(a))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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-Publisher FASB
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
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-Paragraph 9
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-Publisher FASB
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