Earnings Per Share, Calculation of EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Numerator:
Net income	$ 14.9	$ 22.1	$ 67.2	$ (249.9)
Denominator — Weighted-average common shares outstanding (in thousands):
Basic (shares)	17,841	17,123	17,858	17,178
Add: dilutive effect of non-vested common shares, restricted stock units, performance shares and stock options (shares)	334	305	323	0
Add: dilutive effect of warrants (shares)	0	744	0	0
Diluted (shares)	18,175	18,172	18,181	17,178
Net income (loss) per common share:
Basic (in dollars per share)	$ 0.84	$ 1.29	$ 3.76	$ (14.55)
Earnings per common share, Diluted:
Diluted (in dollars per share)	$ 0.82	$ 1.21	$ 3.70	$ (14.55)