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

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

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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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Fair value amount of debt instrument that was repurchased.

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Amount, after accumulated amortization, of debt premium.

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Weighted average interest rate of debt outstanding.

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Present value of lessee's discounted obligation for lease payments from finance lease.

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Present value of lessee's discounted obligation for lease payments from finance lease, classified as current.

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Present value of lessee's discounted obligation for lease payments from finance lease, classified as noncurrent.

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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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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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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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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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Debt (Details) - USD ($)	1 Months Ended	3 Months Ended
Debt (Details) - USD ($)	Mar. 31, 2020	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2015	Apr. 30, 2014	Feb. 28, 2013
Debt Instrument
Total long-term debt	$ 529,667,000	$ 529,667,000		$ 569,788,000
Less: current portion	(364,124,000)	(364,124,000)		0
Total long-term debt, net of current portion	165,543,000	165,543,000		569,788,000
Current installments of long-term debt and finance lease obligations	5,114,000	5,114,000	$ 5,540,000	6,758,000
Finance lease obligations	526,000	526,000	4,886,000	717,000
Total finance lease obligations	5,640,000	5,640,000	10,426,000	7,475,000
Gain on retirement of senior unsecured notes		3,484,000	$ 0
Revolving Loan Facility
Debt Instrument
Total long-term debt	165,543,000	165,543,000		196,414,000
Face amount	$ 400,000,000	$ 400,000,000
Weighted average interest rate	3.93%	3.93%
Unamortized debt issuance costs	$ 4,457,000	$ 4,457,000		4,586,000
Revolving Loan Facility \| LIBOR
Debt Instrument
Applicable margins		3.25%
Revolving Loan Facility \| LIBOR \| Minimum
Debt Instrument
Applicable margins		2.25%
Revolving Loan Facility \| LIBOR \| Maximum
Debt Instrument
Applicable margins		3.50%
Revolving Loan Facility \| Prime Rate \| Minimum
Debt Instrument
Applicable margins		1.25%
Revolving Loan Facility \| Prime Rate \| Maximum
Debt Instrument
Applicable margins		2.50%
Senior Notes \| Senior Notes 7.25%
Debt Instrument
Total long-term debt	364,124,000	$ 364,124,000		373,374,000
Face amount	400,000,000	400,000,000				$ 150,000,000	$ 250,000,000
Unamortized debt issuance costs	$ 599,000	$ 599,000		770,000
Stated interest rate	7.25%	7.25%
Unamortized premium	$ 267,000	$ 267,000		$ 344,000
Repurchase amount	9,344,000	$ 9,344,000			$ 26,200,000
Gain on retirement of senior unsecured notes	$ 3,484,000