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Investments - Net Investment Gains (Losses) by Transaction Type (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2023 | Sep. 30, 2022
Investments, Debt and Equity Securities [Abstract] |  |  |  |
Credit loss impairments | $ 0.0 | $ (0.6) | $ (0.5) | $ (2.8)
Intent-to-sell impairments | (0.6) | (6.2) | (6.7) | (7.6)
Total impairments | (0.6) | (6.8) | (7.2) | (10.4)
Sales and other, net | (3.5) | (3.9) | (25.2) | (3.9)
Change in fair value - equity securities | (1.4) | (4.4) | 5.3 | (34.1)
Change in fair value and gains (losses) realized on settlements - derivatives | (2.9) | 2.3 | (2.6) | 4.6
Net investment losses | $ (8.4) | $ (12.8) | $ (29.7) | $ (43.8)

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- Definition Other than Temporary Impairment Losses, Investments, Portion Recognized In Earnings, Change In Intent + References No definition available. + Details
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- Definition Amount of gain (loss) from the increase (decrease) in fair value of derivative and nonderivative instruments designated as fair value hedging instruments recognized in the income statement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 815 -SubTopic 25 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480238/815-25-50-1 + Details
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