Debt (Details 2) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	May 31, 2015
Debt Instrument, Face Amount			$ 50,000
Total	$ 157,760	$ 158,171
Unsecured Debt [Member]
Total Principal	158,734	159,304
Unamortized debt issuance costs	(974)	(1,133)
Total	157,760	158,171
Unsecured Debt [Member] \| 2019 Term Loan [Member]
Debt Instrument, Face Amount	18,734	19,304
Unsecured Debt [Member] \| 2023 Term Loan [Member]
Debt Instrument, Face Amount	40,000	40,000
Unsecured Debt [Member] \| 2024 Term Loans [Member]
Debt Instrument, Face Amount	$ 100,000	$ 100,000

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.

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- Definition

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

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- Definition

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

Including the current and noncurrent portions, carrying value as of the balance sheet date of uncollateralized debt obligations (with maturities initially due after one year or beyond the operating cycle if longer).

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