Schedule 2 - Parent Company Financial Statements - Statements of Income (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2023	Dec. 31, 2022		Dec. 31, 2021
Condensed Income Statements, Captions [Line Items]
Net Investment Income		$ 419.7	$ 422.6	[1]	$ 427.3	[1]
Income (Loss) from Change in Fair Value of Equity and Convertible Securities		4.7	(79.9)	[1]	114.6	[1]
Net Realized Investment (Losses) Gains		(18.6)	4.3	[1]	64.8	[1]
Impairment Losses		(1.1)	(25.8)	[1]	(11.0)	[1]
Other Income		7.2	9.2	[1]	4.8	[1]
Total Revenues		4,944.2	5,523.9	[1]	5,718.5	[1]
Interest Expense		56.1	54.7		43.6
Loss from Early Extinguishment of Debt		0.0	3.7	[2]	0.0	[1]
Debt Extinguishment, Pension Settlement, and Other Charges		(70.2)
Total Expenses		5,291.3	5,894.9	[1]	5,967.8	[1]
Income Tax Benefit (Expense)		74.8	84.4	[1]	125.6	[1]
Net Loss		(272.3)	(286.6)	[1]	(123.7)	[1]
Net Loss		(272.1)	(286.6)	[1]	(123.7)	[1]
Less: Net Loss attributable to Noncontrolling Interest		(0.2)	0.0	[1]	0.0	[1]
Parent Company
Condensed Income Statements, Captions [Line Items]
Net Investment Income		8.6	16.6		3.4
Income (Loss) from Change in Fair Value of Equity and Convertible Securities		(1.5)	(14.8)		10.0
Net Realized Investment (Losses) Gains		(11.9)	3.0		10.6
Impairment Losses	$ (0.4)	(0.4)	(0.2)		0.0
Other Income		0.0	1.1		0.0
Total Revenues		(5.2)	5.7		24.0
Interest Expense		56.7	52.6		32.0
Debt Extinguishment, Pension Settlement, and Other Charges		70.2	0.0		0.0
Other Operating Expenses		6.1	6.6		5.9
Total Expenses		133.0	59.2		37.9
Loss before Income Taxes and Equity in Net Loss of Subsidiaries		(138.2)	(53.5)		(13.9)
Income Tax Benefit (Expense)		28.4	14.0		(0.6)
Loss before Equity in Net Loss of Subsidiaries		(109.8)	(39.5)		(14.5)
Equity in Net Loss of Subsidiaries		(162.5)	(247.1)		(109.2)
Net Loss		(272.3)	(286.6)		(123.7)
Net Loss		(272.1)	(286.6)		(123.7)
Less: Net Loss attributable to Noncontrolling Interest		$ (0.2)	$ 0.0		$ 0.0

[1] As of January 1, 2023, the Company adopted ASU 2018-12 using the modified retrospective method applied as of the transition date of January 1, 2021. Prior period amounts in the financial statements have been recast to reflect application of the new guidance. See Note 2 to the Consolidated Financial Statements for additional information.

[2] As of January 1, 2023, the Company adopted ASU 2018-12 using the modified retrospective method applied as of the transition date of January 1, 2021. Prior period amounts in the financial statements have been recast to reflect application of the new guidance. See Note 2 to the Consolidated Financial Statements for additional information.