Segment Information - Additional Segment Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Operating revenues	$ 1,037,353	$ 860,400	$ 773,679
Cost of gas	429,635	292,314	262,755
Environmental remediation	12,389	9,938	9,691
Revenue taxes	41,826	34,740	30,291
Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
NGD operating revenues	970,124	797,800	721,950
Other regulated services	19,628	19,087	19,122
Operating revenues	989,752	816,887	741,072
Cost of gas	429,861	292,538	262,980
Environmental remediation	12,389	9,938	9,691
Revenue taxes	41,627	34,600	30,291
NGD margin	$ 505,875	$ 479,811	$ 438,110