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Investment Income and Gains and Losses (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Gain (Loss) on Investments [Line Items]
Net unrealized gains (losses) recognized during the period on equity securities still held	$ 18.4	$ 14.2	$ 6.0
Fixed maturity securities on non-accrual	0.0	0.0	14.8
Impairment losses on investment securities	3.1	5.8	18.0
Impairments on fixed maturities credit related losses			6.9
Allowance for credit losses	8.1	5.7	10.0
Fixed Maturities [Member]
Gain (Loss) on Investments [Line Items]
Impairment losses on investment securities		1.7
Fixed Maturities Intent to Sell Securities [Member]
Gain (Loss) on Investments [Line Items]
Impairment losses on investment securities			11.1
Mortgage Loans on Real Estate [Member]
Gain (Loss) on Investments [Line Items]
Impairment losses on investment securities		4.1
Allowance for credit losses	8.1	5.7
Investments Net Asset Value [Member]
Gain (Loss) on Investments [Line Items]
Net unrealized gains (losses) recognized during the period on equity securities still held	$ (10.0)	$ (8.3)	$ (8.1)

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Amount of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aaa)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479130/326-30-45-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479106/326-30-50-9

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
-Paragraph 9
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479106/326-30-50-9

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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(3)(d)(2))
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
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-Publisher FASB
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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