Long-Term Debt And Notes Payable (Components Of Debt) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Long-term Debt, Excluding Current Maturities	$ 745.3	$ 744.6
Short-term borrowings	0.0	49.6
2.75% Notes Due 2018 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	250.0	250.0
Long-term Debt, Excluding Current Maturities	249.2	248.8
Amortization of Debt Issuance Costs	(0.8)	(1.2)
4.45% Notes Due 2023 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	300.0	300.0
Long-term Debt, Excluding Current Maturities	298.1	297.9
Amortization of Debt Issuance Costs	(1.9)	(2.1)
6.55% Notes Due 2036 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	200.0	200.0
Long-term Debt, Excluding Current Maturities	198.0	197.9
Amortization of Debt Issuance Costs	(1.3)	(1.4)
Debt Instrument, Unamortized Discount	(0.7)	(0.7)
Commercial Paper [Member]
Debt Instrument [Line Items]
Long-term Debt, Excluding Current Maturities	0.0	49.0
Other Liabilities [Member]
Debt Instrument [Line Items]
Long-term Debt, Excluding Current Maturities	$ 0.0	$ 0.6