Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Net Income (Loss)	$ 72.2	$ (146.4)	$ 216.8	$ (323.6)
Other Comprehensive Income Before Income Taxes
Change in Net Unrecognized Postretirement Benefit Costs	(0.7)	61.4	(2.4)	60.3
Gain (Loss) on Cash Flow Hedges	4.9	0.0	1.3	(0.1)
Change in Discount Rate on Future Life Policyholder Benefits	(209.1)	276.8	40.8	217.6
Other Comprehensive Income Before Income Taxes	81.7	8.8	136.4	52.3
Other Comprehensive Income Tax Expense	(16.9)	(1.4)	(28.1)	(10.8)
Other Comprehensive Income, Net of Taxes	64.8	7.4	108.3	41.5
Total Comprehensive Income (Loss)	137.0	(139.0)	325.1	(282.1)
Less: Net Loss attributable to Noncontrolling Interest	(1.5)	(0.1)	(3.6)	(0.1)
Less: Other Comprehensive Income attributable to Noncontrolling Interest	0.0	0.0	0.0	0.0
Less: Total Comprehensive Loss attributable to Noncontrolling Interest	(1.5)	(0.1)	(3.6)	(0.1)
Total Comprehensive Income (Loss)	138.5	(138.9)	328.7	(282.0)
No Credit Losses Recognized in Condensed Consolidated Statements of Income (Loss)
Other Comprehensive Income Before Income Taxes
Changes in Unrealized Holding Gains (Losses) on Investment Securities with:	286.6	(327.9)	98.4	(223.9)
Credit Losses Recognized in Condensed Consolidated Statements of Income (Loss)
Other Comprehensive Income Before Income Taxes
Changes in Unrealized Holding Gains (Losses) on Investment Securities with:	$ 0.0	$ (1.5)	$ (1.7)	$ (1.6)