Retirement Benefits (Net Amount Included In Consolidated Balance Sheets) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	$ 126.7	$ 103.4
Current liabilities	(3.7)	(10.5)
Noncurrent liabilities	(60.1)	(61.0)
Net amount at December 31	62.9	31.9
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	0.0	0.0
Current liabilities	0.0	0.0
Noncurrent liabilities	(233.4)	(250.3)
Net amount at December 31	$ (233.4)	$ (250.3)