Net Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net earnings available to common shareholders	$ 74.4	$ 71.7
Weighted-average common shares outstanding (in millions)
Weighted-average common shares outstanding - basic (in shares)	67.7	72.8
Weighted-average common shares outstanding - diluted (in shares)	68.4	73.5
Net earnings per share - basic (in dollars per share)	$ 1.10	$ 0.98
Net earnings per share - diluted (in dollars per share)	$ 1.09	$ 0.98
Share-based awards
Weighted-average common shares outstanding (in millions)
Antidilutive securities excluded from the calculation of net earnings per share - diluted (in shares)	0.1	0.4
Stock Options
Weighted-average common shares outstanding (in millions)
Effect of dilutive securities	0.2	0.3
Non-Stock Option Awards
Weighted-average common shares outstanding (in millions)
Effect of dilutive securities	0.5	0.4

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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