Schedule II Condensed Financial Information of Registrant - Condensed Statements of Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenues
Net investment income	$ 422.5	$ 357.6	$ 365.1
Net investment gains (losses)	(11.0)	(2.3)	153.3
Total revenues	1,330.1	1,310.4	1,430.5
Expenses
Interest expense	13.9	15.2	15.6
Total benefits, losses and expenses	1,155.2	1,150.8	1,194.1
Income tax expense (benefit)	32.1	26.3	52.0
Net income	142.8	133.3	184.4
Parent company
Revenues
Net investment income	(0.1)	(0.2)	(0.1)
Net investment gains (losses)	0.0	0.0	0.0
Total revenues	(0.1)	(0.2)	(0.1)
Expenses
Interest expense	13.8	14.8	14.3
Other	11.2	5.7	12.6
Total benefits, losses and expenses	25.0	20.5	26.9
Loss before income tax benefit and equity in net earnings of subsidiaries	(25.1)	(20.7)	(27.0)
Income tax expense (benefit)	(5.4)	(5.3)	(6.0)
Loss before equity in net earnings of subsidiaries	(19.7)	(15.4)	(21.0)
Equity in net earnings of subsidiaries	162.5	148.7	205.4
Net income	$ 142.8	$ 133.3	$ 184.4