Net Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net earnings available to common shareholders	$ 115.4	$ 105.7	$ 187.1	$ 171.4
Weighted-average common shares outstanding (in millions)
Weighted-average common shares outstanding - basic (in shares)	71.6	78.3	72.2	78.5
Weighted-average common shares outstanding - diluted (in shares)	72.3	79.3	72.9	79.5
Net earnings per share - basic (in dollars per share)	$ 1.61	$ 1.35	$ 2.59	$ 2.18
Net earnings per share - diluted (in dollars per share)	$ 1.60	$ 1.33	$ 2.57	$ 2.16
Share-Based Awards
Weighted-average common shares outstanding (in millions)
Antidilutive securities excluded from the calculation of net earnings per share - diluted (in shares)	0.4	0.3	0.4	0.3
Stock Options
Weighted-average common shares outstanding (in millions)
Effect of dilutive securities	0.3	0.6	0.3	0.6
Non-Stock Option Awards
Weighted-average common shares outstanding (in millions)
Effect of dilutive securities	0.4	0.4	0.4	0.4