CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Statement of Comprehensive Income [Abstract]
Change in Net Unrealized Gain on Securities Before Adjustment, Tax expense (benefit)	$ (116.1)	$ 110.2
Change in the Effect of Discount Rate ASsumptions on the LIability for Future Policy Benefits, Net of Reinsurance net of tax expense (benefit)	125.9	(42.6)
Change in Net Loss on Derivatives, tax expense (benefit)	(1.0)	11.7
Change in Foreign Currency Translation Adjustment, tax expense (benefit)	0.1	(0.2)
Change in Unrecognized Pension and Postretirement Benefit Costs, tax expense (benefit)	$ 1.0	$ (0.2)