Computations of Basic and Diluted Earnings Per 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 earnings	$ 45.8	$ 102.2	$ 202.3	$ 319.8
Basic weighted average common shares	104.3	103.9	104.4	103.9
Effect of dilutive stock options and employee stock purchase plan shares		0.1		0.1
Effect of restricted shares issued	0.5	0.6	0.5	0.5
Diluted weighted average common shares	104.8	104.6	104.9	104.5
Basic net earnings per share - Continuing operations (in dollars per share)	$ 0.44	$ 0.47	$ 1.94	$ 1.68
Basic net earnings per share - Discontinued operations (in dollars per share)		0.51		1.40
Basic net earnings per share (in dollars per share)	0.44	0.98	1.94	3.08
Diluted net earnings per share - Continuing operations (in dollars per share)	0.44	0.47	1.93	1.67
Diluted net earnings per share - Discontinued operations (in dollars per share)		0.51		1.39
Diluted net earnings per share (in dollars per share)	$ 0.44	$ 0.98	$ 1.93	$ 3.06