Debt (Schedule Of Long-Term Debt) (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Debt Instrument
Unamortized issuing fees	$ (12.6)	$ (13.8)
Total long-term debt	3,866.0	3,855.0
Less: current borrowings	78.5	77.1
Long-term debt	3,787.5	3,777.9
Line of Credit \| Revolving credit facility
Debt Instrument
Long-term debt, gross	0.0	0.0
Line of Credit \| Bilateral credit facilities
Debt Instrument
Long-term debt, gross	0.0	0.0
Commercial paper
Debt Instrument
Long-term debt, gross	1,523.2	1,450.4
Synthetic bonds due 2021
Debt Instrument
Long-term debt, gross	$ 495.9	$ 502.4
Senior Notes \| 3.45% Senior Notes due 2022
Debt Instrument
Interest rate, stated percentage	3.45%	3.45%
Long-term debt, gross	$ 500.0	$ 500.0
Private Placement Notes \| 5.00% 2010 Private placement notes due 2020
Debt Instrument
Interest rate, stated percentage	5.00%	5.00%
Long-term debt, gross	$ 234.0	$ 239.9
Private Placement Notes \| 3.40% 2012 Private placement notes due 2022
Debt Instrument
Interest rate, stated percentage	3.40%	3.40%
Long-term debt, gross	$ 175.5	$ 179.9
Private Placement Notes \| 3.15% 2013 Private placement notes due 2023
Debt Instrument
Interest rate, stated percentage	3.15%	3.15%
Long-term debt, gross	$ 152.1	$ 155.9
Private Placement Notes \| 3.15% 2013 Private placement notes due 2023
Debt Instrument
Interest rate, stated percentage	3.15%	3.15%
Long-term debt, gross	$ 146.3	$ 149.9
Private Placement Notes \| 4.00% 2012 Private placement notes due 2027
Debt Instrument
Interest rate, stated percentage	4.00%	4.00%
Long-term debt, gross	$ 87.8	$ 89.9
Private Placement Notes \| 4.00% 2012 Private placement notes due 2032
Debt Instrument
Interest rate, stated percentage	4.00%	4.00%
Long-term debt, gross	$ 117.0	$ 119.9
Private Placement Notes \| 3.75% 2013 Private placement notes due 2033
Debt Instrument
Interest rate, stated percentage	3.75%	3.75%
Long-term debt, gross	$ 117.0	$ 119.9
Bank borrowings
Debt Instrument
Long-term debt, gross	297.7	332.5
Other
Debt Instrument
Long-term debt, gross	$ 32.1	$ 28.2

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Amount of unamortized debt discount (premium) and debt issuance costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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