Net Income (Loss) Per Common Share - Net Income (Loss) Per Common Share on Basic and Diluted Basis (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Earnings Per Share [Abstract]
Net income (loss)	$ (33.8)	$ (1.0)
Less: Preferred share dividends	2.6	2.6
Net income (loss) attributable to common shareholders	(36.4)	(3.6)
Net income (loss) attributable to common shareholders	$ (36.4)	$ (3.6)
Weighted average common shares outstanding - basic (in shares)	35,099,968	34,891,935
Effect of dilutive securities:
Equity compensation awards (in shares)	0	0
Weighted average common shares outstanding - diluted (in shares)	35,099,968	34,891,935
Net income (loss) per common share:
Basic (in dollars per share)	$ (1.04)	$ (0.11)
Diluted (in dollars per share)	$ (1.04)	$ (0.11)