Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	Preferred Stock and Additional Paid-in Capital	Common Stock	Additional Paid-In Capital	Treasury Shares	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning Balance at Dec. 31, 2022	$ 1,232.9	$ 144.0	$ 46.4	$ 1,395.4	$ (455.1)	$ 407.3	$ (305.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(33.8)					(33.8)
Other comprehensive income (loss) - change in fair value of fixed maturities, net of taxes	45.5						45.5
Other comprehensive income (loss), net of tax	1.2						1.2
Activity under stock incentive plans	1.7		0.1	1.6
Retirement of common stock (tax payments on equity compensation)	(0.8)			(0.8)
Employee stock purchase plan	0.4			0.4
Dividends on Series A Preferred stock	(2.6)					(2.6)
Ending Balance at Mar. 31, 2023	1,244.5	144.0	46.5	1,396.6	(455.1)	370.9	(258.4)
Beginning Balance at Dec. 31, 2023	1,297.5	137.1	1,056.6	51.1	0.0	0.9	51.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	25.6					25.6
Other comprehensive income (loss) - change in fair value of fixed maturities, net of taxes	(15.9)						(15.9)
Other comprehensive income (loss), net of tax	(0.1)						(0.1)
Dividends on Series A Preferred stock	(2.6)					(2.6)
Issuance of common stock	100.0		100.0
Ending Balance at Mar. 31, 2024	$ 1,404.5	$ 137.1	$ 1,156.6	$ 51.1	$ 0.0	$ 23.9	$ 35.8