Schedule of Reclassifications Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2025		Dec. 31, 2024	Dec. 31, 2023
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Net Investment Loss		$ (106.6)		$ (34.6)	$ (36.0)
Impairement Loss		(160.9)	[1]	(2.5)	0.0
Change in Allowance for Credit Losses	[2]	3.1		3.0	2.2
Net Investment Income		2,032.7		2,130.0	2,096.7
Other Expenses		(1,499.0)		(1,222.7)	(1,112.0)
Income Tax Expense (Benefit)		195.0		472.2	356.3
Net Income		738.5		1,779.1	1,283.8
Reclassification out of Accumulated Other Comprehensive Income | Net Unrealized Loss on Securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Net Investment Loss		41.5		(38.2)	(48.7)
Impairement Loss		(160.9)		(2.5)	0.0
Change in Allowance for Credit Losses		(3.1)		(3.0)	(2.2)
Income of Parent Company Before Income Tax		(122.5)		(43.7)	(50.9)
Income Tax Expense (Benefit)		(26.3)		(9.4)	(10.9)
Net Income		(96.2)		(34.3)	(40.0)
Reclassification out of Accumulated Other Comprehensive Income | Net Actuarial Loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Other Expenses		(16.6)		(16.4)	(7.2)
Reclassification out of Accumulated Other Comprehensive Income | Prior Service Credit
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Other Expenses		0.3		0.1	0.2
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Income of Parent Company Before Income Tax		5.1		16.0	33.8
Income Tax Expense (Benefit)		1.1		3.4	7.1
Net Income		4.0		12.6	26.7
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent | Interest Rate Swaps
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Net Investment Loss		(0.9)		0.0	0.0
Net Investment Income		6.7		16.4	34.7
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent | Foreign Exchange Contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Net Investment Loss		(0.6)		(0.2)	(0.4)
Net Investment Income		(0.1)		(0.2)	(0.5)
Reclassification out of Accumulated Other Comprehensive Income | Unrecognized Pension and Postretirement Benefit Costs
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Income of Parent Company Before Income Tax		(120.1)		(16.3)	(7.0)
Income Tax Expense (Benefit)		(26.5)		(3.4)	(1.7)
Net Income		(93.6)		(12.9)	(5.3)
Reclassification out of Accumulated Other Comprehensive Income | Settlement Loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Other Expenses		$ (103.8)		$ 0.0	$ 0.0

[1] Our investment gains and losses on fixed maturity securities for the year ended December 31, 2025 were driven primarily by the Closed Block long-term care and Unum US individual disability reinsurance transaction (Fortitude Re reinsurance transaction) which resulted in a net loss of $46.8 million. In addition, for the year ended December 31, 2025, we realized a $19.1 million loss on sales of fixed maturity securities relating to funding of a dividend from one of our subsidiaries.

[2] ncludes reduction of allowance on securities sold or otherwise disposed during the period.