Earnings Per Share (Reconciliation of Earnings to Earnings Attributable to Common Shares Used in Basic and Diluted Calculation) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Abstract]
Earnings from continuing operations	$ 47.6	$ 43.7	$ 88.8	$ 79.2
Earnings allocated to participating non-vested share awards	(0.2)	(0.1)	(0.3)	(0.3)
Earnings from continuing operations attributable to common shares	$ 47.4	$ 43.6	$ 88.5	$ 78.9

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

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