Represents the number of tranches comprising the debt issuance.

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Represents the lump sum amount payable at the maturity of the debt instrument.

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No definition available.

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Represents the percentage of annual amortization of term loan after specified period.

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No definition available.

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Represents the percentage of annual amortization of term loan through specified period.

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Represents the redemption price as a percentage of the principal amount at which the debt instrument may be required to be redeemed by the entity in the event of a change of control or downgrade of the entity's credit rating.

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No definition available.

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- Definition

The contingent increase above the maximum borrowing capacity under the credit facility, if any one or more of the existing banks or new banks agree to provide such increased commitment amount.

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No definition available.

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- Definition

The number of financial covenants.

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No definition available.

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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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No definition available.

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The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

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No definition available.

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- Definition

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

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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.

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No definition available.

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Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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No definition available.

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- Definition

Represents the aggregate of total long-term debt, including current maturities and short-term debt.

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No definition available.

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Weighted average interest rate of debt outstanding.

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No definition available.

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

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No definition available.

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- Definition

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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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
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
-Paragraph 1
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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

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- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

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- References

No definition available.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
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-Subparagraph (SX 210.12-04.(a))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
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-Name Accounting Standards Codification
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-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

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No definition available.

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Debt - Other (Details) $ in Millions		1 Months Ended		12 Months Ended
Debt - Other (Details) $ in Millions	Apr. 12, 2013 USD ($)	Sep. 30, 2016 USD ($)	Nov. 30, 2006 USD ($) tranche	Dec. 31, 2017 USD ($) item	Dec. 31, 2016 USD ($)	Nov. 15, 2016 USD ($)
Debt
Total				$ 1,914.5	$ 1,945.0
Number of financial covenants \| item				2
Aggregate maturities of long-term debt for each of the next five years and thereafter
2018				$ 92.0
2019				60.6
2020				60.6
2021				943.6
2022				0.3
Thereafter				757.4
Credit Agreement
Debt
Maximum borrowing capacity		$ 2,100.0
Debt term		5 years
Unsecured revolving credit facility due September 30, 2021
Debt
Maximum borrowing capacity		$ 1,500.0
Total				$ 538.0	$ 540.0
Additional maximum borrowing capacity under the credit agreement subject to approval of the lenders and certain other conditions		500.0
Commitment fee on unused portion of revolving credit facility (as a percent)				0.15%
Weighted average fixed interest rate (as a percent)				2.96%	2.16%
Letters of credit outstanding				$ 53.3
Available on the revolving credit facility				$ 908.7
Unsecured revolving credit facility due September 30, 2021 \| LIBOR
Debt
Variable interest rate				LIBOR
Interest rate added to base (as a percent)				1.25%
Unsecured revolving credit facility due September 30, 2021 \| Bank prime rate
Debt
Variable interest rate				bank prime rate
Interest rate added to base (as a percent)				0.25%
Unsecured term loan due from March 30, 2018 to September 30, 2021
Debt
Maximum borrowing capacity		$ 600.0
Total				$ 562.5	$ 600.0
Annual amortization of term loan through September 2018 (as a percent)		5.00%
Annual amortization of term loan thereafter until June 2021 (as a percent)		10.00%
Weighted average fixed interest rate (as a percent)				2.82%	2.02%
Unsecured term loan due from March 30, 2018 to September 30, 2021 \| LIBOR
Debt
Variable interest rate				LIBOR
Interest rate added to base (as a percent)				1.25%
Unsecured term loan due from March 30, 2018 to September 30, 2021 \| Bank prime rate
Debt
Variable interest rate				bank prime rate
Interest rate added to base (as a percent)				0.25%
Senior Unsecured Notes
Debt
Percentage of principal amount at which the notes may be required to be repurchased in event of a change of control and a downgrade of the entity's credit rating				101.00%
Senior unsecured notes issued November 20, 2006
Debt
Issuance of debt			$ 600.0
Number of tranches comprising the debt issuance \| tranche			2
Senior unsecured notes due November 15, 2016
Debt
Total						$ 0.0
Interest rate (as a percent)			6.20%
Lump sum payment on maturity						$ 350.0
Issuance of debt			$ 350.0
Senior unsecured notes due April 15, 2023
Debt
Total				$ 500.0	$ 500.0
Interest rate (as a percent)	4.50%
Issuance of debt	$ 500.0
Senior unsecured notes due November 15, 2036
Debt
Total				250.0	250.0
Interest rate (as a percent)			6.85%
Issuance of debt			$ 250.0
Other notes and revolving credit facilities
Debt
Maximum borrowing capacity				70.3
Lines of credit				53.9	44.4
IRB
Debt
Total				$ 10.1	$ 10.6