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Investments - Aging of Gross Unrealized Losses (Details) - USD ($) $ in Millions | Jun. 30, 2026 | Dec. 31, 2025
--- | --- | ---
Fair Value |  |
Less than 12 Months | $ 640.2 | $ 53.5
12 Months or More | 0.0 | 4.9
Fair Value | 640.2 | 58.4
Gross Unrealized Losses |  |
Less than 12 Months | (4.0) | 0.0
12 Months or More | 0.0 | 0.0
Gross Unrealized Losses | (4.0) | 0.0
Corporate debt securities |  |
Fair Value |  |
Less than 12 Months | 411.6 | 45.9
12 Months or More | 0.0 | 4.9
Fair Value | 411.6 | 50.8
Gross Unrealized Losses |  |
Less than 12 Months | (2.1) | 0.0
12 Months or More | 0.0 | 0.0
Gross Unrealized Losses | (2.1) | 0.0
U.S. Government obligations |  |
Fair Value |  |
Less than 12 Months | 144.2 | 0.4
12 Months or More | 0.0 | 0.0
Fair Value | 144.2 | 0.4
Gross Unrealized Losses |  |
Less than 12 Months | (1.5) | 0.0
12 Months or More | 0.0 | 0.0
Gross Unrealized Losses | (1.5) | 0.0
Asset-backed securities and collateralized loan obligations |  |
Fair Value |  |
Less than 12 Months | 63.4 | 0.0
12 Months or More | 0.0 | 0.0
Fair Value | 63.4 | 0.0
Gross Unrealized Losses |  |
Less than 12 Months | (0.3) | 0.0
12 Months or More | 0.0 | 0.0
Gross Unrealized Losses | (0.3) | 0.0
Non-U.S. government obligations |  |
Fair Value |  |
Less than 12 Months | 21.0 | 7.2
12 Months or More | 0.0 | 0.0
Fair Value | 21.0 | 7.2
Gross Unrealized Losses |  |
Less than 12 Months | (0.1) | 0.0
12 Months or More | 0.0 | 0.0
Gross Unrealized Losses | $ (0.1) | $ 0.0

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