Earnings (Loss) per Common Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings (Loss) per Common Share
Net income	$ 9.0	$ 2.2	$ 0.1	$ 11.4	$ 9.7	$ 8.4	$ 11.3	$ 29.5
Basic weighted-average shares	81,771,279			80,885,244			81,475,814	80,639,099
Effect of dilutive securities:
Restricted stock awards	1,258,777			219,661			1,057,473	425,589
Diluted weighted-average shares	83,030,056			81,104,905			82,533,287	81,064,688
Basic earnings per share (in dollars per share)	$ 0.11			$ 0.14			$ 0.14	$ 0.37
Diluted earnings per share (in dollars per share)	$ 0.11			$ 0.14			$ 0.14	$ 0.36