Loss Per Share (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
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Basic and dilutive net income available to common shareholders	$ 13.9	$ 19.8	$ 29.0	$ 24.2
Basic weighted average shares outstanding	32,466	32,065	32,398	31,602
Dilutive weighted average shares outstanding	33,194	32,621	32,915	32,569
Basic earnings per share (in dollars per share)	$ 0.43	$ 0.62	$ 0.89	$ 0.76
Diluted earnings per share (in dollars per share)	$ 0.42	$ 0.61	$ 0.88	$ 0.74
Anti-dilutive securities excluded from computation of earnings per share			213	264
Unvested shares and stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Effect of dilutive securities:	728	556	517	646
Series B Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Effect of dilutive securities:	0	0	0	321