Fair Value Measurements (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Interest Rate Swap [Abstract]
Term of debt on utilities rated A- used to discount prospective cash flows	30 years
Reduction in fair value of swap liability	$ 151
Fair Value Measurements [Abstract]
Customers' advances for construction	7,934	$ 6,849
Note receivable	255	255
Fair Value on a Recurring Basis [Member]
Interest Rate Swap [Abstract]
Interest rate swap	2,200	1,815
Fair Value on a Recurring Basis [Member] | Fair Value Measurements at Reporting Date Using Significant Other Observable Inputs (Level 2) [Member]
Interest Rate Swap [Abstract]
Interest rate swap	2,200	1,815
Carrying Amount [Member]
Fair Value, Financial Liabilities [Abstract]
Total long-term debt	98,745	95,908
Estimated Fair Value [Member]
Fair Value, Financial Liabilities [Abstract]
Total long-term debt	$ 116,000	$ 105,000