Taxes Other than Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Components of Taxes Other than Income Taxes [Abstract]
Regulatory Assessment	$ 231	$ 243	$ 242
Property	344	339	334
Payroll, net of amounts capitalized	539	530	510
Capital Stock	0	1	42
Other	19	1	1
Total taxes other than income taxes	$ 1,133	$ 1,114	$ 1,129