Earnings (Loss) Per Common Share - Computation of Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Net earnings	$ 42.3	$ 6.1
Participating warrants dividend	0.0	(0.9)
Series A preferred stock dividend	0.0	(14.4)
Accretion of Series A preferred stock	0.0	(4.5)
Other securities dividends	0.0	(0.2)
Earnings attributable to other participating securities	(2.0)	0.0
Earnings (loss) attributable to common shareholders	$ 40.3	$ (13.9)
Basic weighted average common shares outstanding (in shares)	46.0	45.6
Basic earnings (loss) per common share (in usd per share)	$ 0.88	$ (0.30)
Dilutive effect of stock options and equivalents (in shares)	0.0	0.0
Diluted weighted-average shares outstanding (in shares)	46.0	45.6
Diluted earnings (loss) attributable to common shareholders	$ 40.3	$ (13.9)
Diluted earnings (loss) per common share (in usd per share)	$ 0.88	$ (0.30)