Net (Loss) Income Per Common Stock - Net (Loss) Income Per Common Share on Basic and Diluted Basis (Detail) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	2 Months Ended	11 Months Ended	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2023	Nov. 15, 2023	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share [Abstract]
Net income (loss)	$ 0.9	$ 0.9	$ (210.4)	$ (175.2)	$ 6.7
Dividends on Series A Preferred stock		0.0	10.5	10.5	10.5
Net income (loss) attributable to common shareholders, diluted		0.9	(220.9)	(185.7)	(3.8)
Net income (loss) attributable to common shareholders, basic		$ 0.9	$ (220.9)	$ (185.7)	$ (3.8)
Weighted average common shares outstanding - basic (in shares)			35,166,679	34,980,608	34,816,160
Effect of dilutive securities:
Equity compensation awards (in shares)			0	0	0
Weighted average common shares outstanding - diluted (in shares)			35,166,679	34,980,608	34,816,160
Net income (loss) per common stock:
Basic (in dollars per share)			$ (6.28)	$ (5.31)	$ (0.11)
Diluted (in dollars per share)			$ (6.28)	$ (5.31)	$ (0.11)