Earnings Per Share (Reconciliation of Net Earnings to Net Earnings Attributable to Common Shares Used in Basic and Diluted Calculation) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Earnings from continuing operations	$ 242.3	$ 189.6	$ 220.6
Earnings allocated to participating non-vested share awards	(0.5)	(0.6)	(0.7)
Earnings from continuing operations attributable to common shares	$ 241.8	$ 189.0	$ 219.9

Amount after tax of income (loss) from continuing operations attributable to the parent.

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