Long-Term Debt (Details Of Long-Term Debt, Weighted Average Interest Rates And Due Dates) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Long-term debt	$ 959.8	$ 944.9
Less current maturities	3.6	3.4
Noncurrent portion of long-term debt	956.2	941.5
Term notes
Debt Instrument [Line Items]
Long-term debt	$ 745.3	$ 744.4
Year-end Interest Rate	(3.80%)	(3.80%)
Due Date Through	2024	2024
Industrial development bonds, principally variable interest rates
Debt Instrument [Line Items]
Long-term debt	$ 12.5	$ 14.8
Year-end Interest Rate	(0.90%)	(0.30%)
Due Date Through	2030	2030
Commercial paper
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	1.00%	0.50%
Long-term debt	$ 195.9	$ 181.5
Year-end Interest Rate	(100.00%)	(100.00%)
Due Date Through	2021	2019
Capitalized leases (primarily machinery, vehicle and office equipment)
Debt Instrument [Line Items]
Long-term debt	$ 5.7	$ 4.2
Capitalized leases (primarily machinery, vehicle and office equipment)
Debt Instrument [Line Items]
Long-term debt	$ 0.4	$ 0.0
Net Commercial Paper Activity [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	0.80%	0.50%

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- Definition

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Weighted average interest rate of debt outstanding.

+ References

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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 of long-term debt and capital lease obligation due after one year or beyond the normal operating cycle, if longer.

+ References

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

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Amount of long-term debt and capital leases due within one year or the normal operating cycle, if longer.

+ References

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 210.5-02.20)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Weighted average interest rate of long-term debt outstanding.

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