Face (par) amount of debt instrument at time of issuance.

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- Definition

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

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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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- 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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- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

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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.

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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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- 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.

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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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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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- Definition

Write-off of amounts previously capitalized as debt issuance cost in an extinguishment of debt.

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Long-Term Debt (Narrative) (Details) - USD ($)	6 Months Ended
Long-Term Debt (Narrative) (Details) - USD ($)	Jun. 30, 2019	Jan. 24, 2019	Dec. 31, 2018	Mar. 31, 2013	Jan. 31, 2013
Debt Instrument [Line Items]
Carrying value of outstanding debt	$ 0		$ 210,400,000
Unamortized debt issuance costs			1,600,000
Current maturities of long-term debt	$ 0		208,805,000
Senior Subordinated Notes [Member]
Debt Instrument [Line Items]
Debt instrument, issued value			$ 210,000,000.0
Senior Subordinated Notes, interest rate			6.25%
Other Debt Obligations [Member]
Debt Instrument [Line Items]
Carrying value of outstanding debt			$ 2,000,000.0
Senior Subordinated 6.25% Notes
Debt Instrument [Line Items]
Carrying value of outstanding debt			$ 210,000,000
Debt instrument, issued value					$ 210,000,000
Senior Subordinated Notes, interest rate	6.25%		6.25%	6.25%
Write off of deferred debt issuance cost	$ 1,100,000
Revolving Credit Facility \| Senior Credit Agreement
Debt Instrument [Line Items]
Revolving credit facility, availability amount	394,000,000.0
Borrowings outstanding	0		$ 0
Standby Letters of Credit \| Senior Credit Agreement
Debt Instrument [Line Items]
Letters of credit issued	$ 6,000,000.0
Line of Credit \| 2019 Senior Credit Agreement
Debt Instrument [Line Items]
Current borrowing capacity		$ 400,000,000
Letters of credit issued		700,000,000
Medium-term Notes \| 2019 Senior Credit Agreement
Debt Instrument [Line Items]
Debt instrument, issued value		$ 300,000,000