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Derivative Instruments - Pre-tax Portion of the Fair Value of Foreign Currency Forward Contracts and Foreign Currency Options (Details) - USD ($) $ in Millions | 6 Months Ended
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Jun. 30, 2025 | Jun. 30, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract] |  |
Unrealized gains | $ 17.9 | $ 50.6
Unrealized (losses) | (153.1) | (0.3)
Net unrealized gains (losses) | $ (135.2) | $ 50.3

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