Earnings (Loss) Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Net income (loss) to common shareholders	$ 35.1	$ (19.9)	$ 55.1	$ 29.6
Basic weighted average shares outstanding	235.9	229.5	232.7	229.2
Diluted weighted average shares outstanding	240.9	229.5	239.1	229.3
Earnings (loss) per Common Share:
Basic net income (loss) per share (dollars per share)	$ 0.15	$ (0.09)	$ 0.24	$ 0.13
Diluted net income (loss) per share (dollars per share)	$ 0.15	$ (0.09)	$ 0.23	$ 0.13
Antidilutive securities excluded from computation of earnings per share (in shares)	1.1	17.2	0.6	13.4