Debt (Schedule Of Long-Term Debt) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Debt Instrument [Line Items]
Revolving credit facility			$ 100.0
Commercial paper (1)	821.8	[1]	669.8
Term loan	27.1		26.8
Property financing	16.2		16.7
Total long-term debt	1,664.1		1,612.2
Less: current portion	(32.1)		(31.8)
Long-term debt, less current portion	1,632.0		1,580.4
Commercial Paper [Member]
Debt Instrument [Line Items]
Commercial paper borrowings weighted average interest rate, as a percent	0.38%
SeniorNotes2017 [Member]
Debt Instrument [Line Items]
Debt Instrument, interest rate, as a percent	2.00%		2.00%
Senior Notes, Noncurrent	299.4		299.3
SeniorNotes2022 [Member]
Debt Instrument [Line Items]
Debt Instrument, interest rate, as a percent	3.45%		3.45%
Senior Notes, Noncurrent	$ 499.6		$ 499.6

[1] At March 31, 2013, committed credit available under our revolving credit facility provided the ability to refinance our commercial paper obligations on a long-term basis. As we have both the ability and intent to refinance these obligations on a long-term basis, our commercial paper borrowings were classified as long-term in the condensed consolidated balance sheet at March 31, 2013. As of March 31, 2013, our commercial paper borrowings had a weighted average interest rate of 0.38%.