Long-Term Debt - Long-term debt and lease financing obligations (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Term loans payable	$ 49,315	$ 47,844
Lease financing obligations	0	58
Total long-term debt and lease financing obligations	49,315	47,902
Unamortized debt issuance costs	(384)	(478)
Current portion of lease financing obligations	0	(58)
Long-term debt and lease financing obligations, net of debt issuance costs and current portion	48,931	47,366
Term Loan Agreement
Debt Instrument [Line Items]
Term loans payable	49,300	47,800
Current portion of lease financing obligations	$ 0	$ (58)

Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

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Amount of capital lease obligation due within one year or the normal operating cycle, if longer.

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Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

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

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

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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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