Nature Of Operations And Significant Accounting Policies (Computation Of Basic And Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accounting Policies [Abstract]
Less: Noncontrolling interest in subsidiaries’ earnings									$ 1.0	$ 1.1	$ 0.9	$ 0.9
Net income attributable to common shareholders	$ (63.9)	$ 63.5	$ 68.2	$ 55.0					$ 122.8	$ 228.9	$ 192.7	$ 192.7
Weighted average basic shares outstanding									58.5	58.1	58.7
Effect of dilutive stock options									0.8	0.7	0.9
Average diluted shares outstanding									59.3	58.8	59.6
Earnings per share - diluted:
Earnings Per Share, Basic	$ (1.11)	$ 1.09	$ 1.17	$ 0.95	$ 1.12	$ 0.98	$ 0.96	$ 0.88	$ 2.10	$ 3.94	$ 3.28
Earnings Per Share, Diluted	$ (1.08)	$ 1.07	$ 1.15	$ 0.93	$ 1.10	$ 0.97	$ 0.95	$ 0.87	$ 2.07	$ 3.89	$ 3.23