Net Income Per Share - Schedule of Calculation of Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Numerator:
Net income	$ 4.5	$ 29.1
Denominator – Weighted-average common shares outstanding (in thousands):
Basic	15,805,000	15,838,000
Add: dilutive effect of non-vested common shares, restricted stock units and performance shares	182,000	170,000
Diluted	15,987,000	16,008,000
Net income per common share, Basic:	$ 0.28	$ 1.83
Net income per common share, Diluted:	$ 0.28	$ 1.81