Investments (Schedule of Amortized Cost of Mortgage Loan Participations by Credit Ratings and Year of Origination) (Details) $ in Millions	Dec. 31, 2025 USD ($)
Schedule of Investments [Line Items]
Allowance for credit losses	$ (8.1)
Amortized cost, net of allowance for credit losses	247.0
Amortized Cost
Schedule of Investments [Line Items]
Prior to 2021	162.7
2021	54.2
2022	10.0
2023	0.0
2024	18.8
2025	9.4
Total	255.1
Aaa/Aa/A
Schedule of Investments [Line Items]
Prior to 2021	87.0
2021	42.5
2022	10.0
2023	0.0
2024	0.0
2025	0.0
Total	139.5
Baa
Schedule of Investments [Line Items]
Prior to 2021	43.7
2021	11.7
2022	0.0
2023	0.0
2024	9.9
2025	9.4
Total	74.7
Ba and lower
Schedule of Investments [Line Items]
Prior to 2021	32.0
2021	0.0
2022	0.0
2023	0.0
2024	8.9
2025	0.0
Total	$ 40.9

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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