Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Basic and dilutive net income (loss) available to common shareholders	$ 19.0	$ 27.1	$ (6.3)	$ 15.1
Basic weighted average shares outstanding (in shares)	32,715	32,459	32,642	32,362
Unvested shares and stock units (in shares)	607	395	0	452
Dilutive weighted average shares outstanding (in shares)	33,322	32,854	32,642	32,814
Basic earnings per share (in dollars per share)	$ 0.58	$ 0.84	$ (0.19)	$ 0.47
Diluted earnings per share (in dollars per share)	$ 0.57	$ 0.83	$ (0.19)	$ 0.46
Antidillutive options and shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share		497	350