Schedule II Condensed Financial Information of Registrant - Condensed Statements of Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenues
Net investment income	$ 400.9	$ 422.5	$ 357.6
Net investment losses	(56.5)	(11.0)	(2.3)
Total revenues	1,382.9	1,330.1	1,310.4
Expenses
Interest expense	19.4	13.9	15.2
Total benefits, losses and expenses	1,394.8	1,155.2	1,150.8
Income tax expense (benefit)	(9.3)	32.1	26.3
Net income (loss)	(2.6)	142.8	133.3
Parent company
Revenues
Net investment income	0.0	(0.1)	(0.2)
Total revenues	0.0	(0.1)	(0.2)
Expenses
Interest expense	19.4	13.8	14.8
Other	8.5	11.2	5.7
Total benefits, losses and expenses	27.9	25.0	20.5
Loss before income tax benefit and equity in net earnings of subsidiaries	(27.9)	(25.1)	(20.7)
Income tax expense (benefit)	(6.3)	(5.4)	(5.3)
Loss before equity in net earnings of subsidiaries	(21.6)	(19.7)	(15.4)
Equity in net earnings (losses) of subsidiaries	19.0	162.5	148.7
Net income (loss)	$ (2.6)	$ 142.8	$ 133.3