Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Net unrealized investment gains (losses) on fixed maturity securities, net of tax
Beginning balance	$ 1,807.4
Other comprehensive income (loss) before reclassifications	(284.8)	$ (129.1)
Amounts reclassified from AOCI	14.1	6.4
Other comprehensive loss	(270.7)	(122.7)
Ending balance	1,536.8	1,692.9
Pretax reclassification amounts from AOCI, tax	(3.8)	(1.7)
Total
Net unrealized investment gains (losses) on fixed maturity securities, net of tax
Beginning balance	280.5	355.1
Ending balance	9.8	232.4
Net Unrealized Investment Gains (Losses) on Securities
Net unrealized investment gains (losses) on fixed maturity securities, net of tax
Beginning balance	290.7	366.3
Other comprehensive income (loss) before reclassifications	(284.8)	(129.1)
Amounts reclassified from AOCI	14.1	6.4
Other comprehensive loss	(270.7)	(122.7)
Ending balance	20.0	243.6
Pretax reclassification amounts from accumulated other comprehensive income (loss)	(17.9)	(8.1)
Net Funded Status of Benefit Plans
Net unrealized investment gains (losses) on fixed maturity securities, net of tax
Beginning balance	(10.2)	(11.2)
Other comprehensive income (loss) before reclassifications	0.0	0.0
Amounts reclassified from AOCI	0.0	0.0
Other comprehensive loss	0.0	0.0
Ending balance	$ (10.2)	$ (11.2)

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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