Income Taxes - Components of Federal and State Income Tax Provisions (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income tax (expense) benefit:
Current expense (benefit)	$ 17.5	$ 13.6	$ 6.7
Deferred expense (benefit)	367.0	349.6	125.1
Total income tax expense (benefit)	$ 384.5	$ 363.2	$ 131.8

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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+ Details