Earnings per Common Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Earnings Per Share, Basic and Diluted [Line Items]
Net income	$ 29.3	$ 41.6
Weighted average common shares outstanding for basic earnings per share computation (in shares)	64,790,186	60,311,171
Dilutive effects of stock-based compensation (in shares)	146,921	286,899
Weighted average common shares outstanding for diluted earnings per common share computation (in shares)	64,937,107	60,598,070
Basic earnings per common share (in dollars per share)	$ 0.45	$ 0.69
Diluted earnings per common share (in dollars per share)	$ 0.45	$ 0.69
Restricted Stock
Earnings Per Share, Basic and Diluted [Line Items]
Anti-dilutive unvested time restricted stock (in shares)	113,468	121,452
Unvested restricted stock
Earnings Per Share, Basic and Diluted [Line Items]
Anti-dilutive unvested time restricted stock (in shares)	309,410		154,387