Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Income (Loss) from Continuing Operations Attributable to Parent					$ (70.8)	$ 146.8	$ 175.2
Numerator:
Less: undistributed earnings allocated to nonvested stock					0.0	0.0	(0.2)
Net income available to common shareholders for basic earnings per share and diluted earnings per share					$ (70.8)	$ 146.8	$ 175.0
Denominator:
Weighted-average number of shares outstanding - basic					84,631,778	90,367,345	94,989,561
Effect of dilutive securities:
Stock options and awards - based on the treasury stock method (in shares)					0	856,983	834,167
Weighted-average number of shares outstanding, assuming dilution of stock options and awards					84,631,778	91,224,328	95,823,728
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.46	$ (0.12)	$ 0.62	$ 0.64	$ (0.84)	$ 1.62	$ 1.84
Income (Loss) from Continuing Operations, Per Diluted Share	$ 0.46	$ (0.12)	$ 0.61	$ 0.64	$ (0.84)	$ 1.61	$ 1.82