Taxes Other Than Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Taxes Other Than Income [Line Items]
Total taxes other than income	$ 15,201	$ 15,564	$ 45,038	$ 45,360
Property [Member]
Taxes Other Than Income [Line Items]
Total taxes other than income	7,020	7,019	20,415	20,542
Gross Receipts, Excise And Franchise [Member]
Taxes Other Than Income [Line Items]
Total taxes other than income	3,423	3,940	10,181	10,994
Payroll [Member]
Taxes Other Than Income [Line Items]
Total taxes other than income	2,216	2,175	7,988	7,630
Regulatory Assessments [Member]
Taxes Other Than Income [Line Items]
Total taxes other than income	718	747	2,213	2,001
Pumping Fees [Member]
Taxes Other Than Income [Line Items]
Total taxes other than income	1,726	1,599	3,967	4,014
Other [Member]
Taxes Other Than Income [Line Items]
Total taxes other than income	$ 98	$ 84	$ 274	$ 179