Long-Term Debt (Schedule Of Long-Term Debt Instruments) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Floating rate credit facility expiring December 17, 2018	$ 0us-gaap_LineOfCredit
Long-term debt	1,589.3us-gaap_LongTermDebt	1,588.6us-gaap_LongTermDebt
Unsecured Debt [Member] \| Floating Rate Credit Facility Expiring December 17, 2018 [Member]
Debt instrument due date	Dec. 17, 2018
Unsecured Debt [Member] \| Due January 30, 2024 [Member]
Unsecured Senior Notes	596.2
Debt instrument, interest rate, stated percentage		4.00%
Debt instrument due date	Jan. 30, 2024
Unsecured Debt [Member] \| Due November 30, 2043 [Member]
Unsecured Senior Notes	393.5
Debt instrument, interest rate, stated percentage		5.375%
Debt instrument due date	Nov. 30, 2043
Unsecured Debt [Member] \| Due November 30, 2022 [Member]
Unsecured Senior Notes	599.6
Debt instrument, interest rate, stated percentage		3.125%
Debt instrument due date	Nov. 30, 2022
Carrying Value [Member]
Long-term debt	1,589.3	1,588.6
Carrying Value [Member] \| Floating Rate Credit Facility Expiring December 17, 2018 [Member]
Floating rate credit facility expiring December 17, 2018	0	0
Carrying Value [Member] \| Unsecured Debt [Member] \| Due January 30, 2024 [Member]
Unsecured Senior Notes	596.2	595.8
Carrying Value [Member] \| Unsecured Debt [Member] \| Due November 30, 2043 [Member]
Unsecured Senior Notes	393.5	393.2
Carrying Value [Member] \| Unsecured Debt [Member] \| Due November 30, 2022 [Member]
Unsecured Senior Notes	599.6	599.6
Fair Value [Member]
Long-term debt	1,695.8	1,544.7
Fair Value [Member] \| Floating Rate Credit Facility Expiring December 17, 2018 [Member]
Floating rate credit facility expiring December 17, 2018	0	0
Fair Value [Member] \| Unsecured Debt [Member] \| Due January 30, 2024 [Member]
Unsecured Senior Notes	625.9	593.2
Fair Value [Member] \| Unsecured Debt [Member] \| Due November 30, 2043 [Member]
Unsecured Senior Notes	473.1	400.0
Fair Value [Member] \| Unsecured Debt [Member] \| Due November 30, 2022 [Member]
Unsecured Senior Notes	$ 596.8	551.5

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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