Investments - Equity Securities Gains (Losses) (Details) - USD ($) $ in Millions |
3 Months Ended | |
|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
|
| Investments, Debt and Equity Securities [Abstract] | ||
| Net losses recognized during the period on equity securities | $ (0.3) | $ (10.3) |
| Less: net gains (losses) recognized during the period on equity securities sold, transferred or disposed during the period | 0.0 | 0.0 |
| Unrealized losses recognized during the reporting period on equity securities held at the reporting date | $ (0.3) | $ (10.3) |