CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Millions	Total	Common Stock	Net Parent Investment	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning Balance at Dec. 31, 2022	$ 455.6	$ 0.0	$ 511.4	$ 0.0	$ 0.0	$ (55.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	98.9		84.1		14.8
Other comprehensive loss, net of tax	(2.1)					(2.1)
Net transfers to Parent	(550.9)		(595.5)	44.6
Ending Balance at Jun. 30, 2023	1.5	0.0	0.0	44.6	14.8	(57.9)
Beginning Balance at Mar. 31, 2023	472.8	0.0	527.7	0.0	0.0	(54.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	46.2		31.4		14.8
Other comprehensive loss, net of tax	(3.0)					(3.0)
Net transfers to Parent	(514.5)		(559.1)	44.6
Ending Balance at Jun. 30, 2023	1.5	0.0	0.0	44.6	14.8	(57.9)
Beginning Balance at Dec. 31, 2023	80.7	0.0	0.0	49.7	87.2	(56.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	101.7				101.7
Other comprehensive loss, net of tax	(10.8)					(10.8)
Share-based awards	6.5			6.5
Ending Balance at Jun. 30, 2024	178.1	0.0	0.0	56.2	188.9	(67.0)
Beginning Balance at Mar. 31, 2024	121.8	0.0	0.0	52.1	132.7	(63.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	56.2				56.2
Other comprehensive loss, net of tax	(4.0)					(4.0)
Share-based awards	4.1			4.1
Ending Balance at Jun. 30, 2024	$ 178.1	$ 0.0	$ 0.0	$ 56.2	$ 188.9	$ (67.0)