Segment Information - Additional Segment Information - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Operating revenues	$ 93,284	$ 90,317	$ 513,406	$ 499,108
Cost of gas	23,741	22,603	173,489	163,167
Environmental remediation	867	967	6,494	7,258
Operating Segments [Member] \| Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Natural Gas Distribution revenues	79,357	77,916	474,989	472,691
Other regulated services	4,404	5,147	14,251	7,397
Operating revenues	83,761	83,063	489,240	480,088
Cost of gas	23,797	22,659	173,657	163,335
Environmental remediation	867	967	6,494	7,258
Revenue taxes	3,555	3,534	19,752	19,956
NGD margin	$ 55,542	$ 55,903	$ 289,337	$ 289,539

The charge against earnings in the period for known or estimated future costs arising from requirements to perform environmental remediation activities.

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