Earnings (Loss) per Common Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings (Loss) per Common Share
Net income	$ 2.2	$ 0.1	$ 9.7	$ 8.4	$ 2.3	$ 18.1
Basic weighted-average shares	81,612,359		80,675,392		81,325,795	80,513,361
Effect of dilutive securities:
Restricted stock awards	990,839		235,284		765,508	389,671
Diluted weighted-average shares	82,603,198		80,910,676		82,091,303	80,903,032
Basic earnings per share (in dollars per share)	$ 0.03		$ 0.12		$ 0.03	$ 0.22
Diluted earnings per share (in dollars per share)	$ 0.03		$ 0.12		$ 0.03	$ 0.22