Earnings Per Share, Calculation of EPS (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Numerator:
Net income	$ 15.9		$ 25.4		$ 56.2		$ 77.5
Denominator — Weighted-average common shares outstanding (in thousands):
Basic	17,707	[1]	18,548	[1]	17,853	[1]	18,915	[1]
Add: dilutive effect of non-vested common shares, restricted stock units and performance shares	134		165		143		167
Add: dilutive effect of warrants	778		345		596		185
Diluted	18,619	[2]	19,058	[2]	18,592	[2]	19,267	[2]
Earnings per common share, Basic:
Net income per share	$ 0.90		$ 1.37		$ 3.15		$ 4.09
Earnings per common share, Diluted:
Net income per share	$ 0.85		$ 1.34		$ 3.02		$ 4.02

[1] The basic weighted-average number of common shares outstanding during the period excludes non-vested common shares, restricted stock units, performance shares and market-based shares.

[2] The diluted weighted-average number of common shares outstanding during the periods were calculated using the treasury method.