Segment Information - Schedule of Reporting Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Revenues	$ 888,696	$ 791,226	$ 2,596,024	$ 2,384,793	$ 3,510,104	$ 3,232,930
Segment net income (loss)	(11,576)	18,273	130,836	128,780	234,380	220,498
Revenues from external customers
Segment Reporting Information [Line Items]
Revenues	861,854	759,134	2,521,295	2,282,576	3,402,733	3,094,096
Intersegment revenues
Segment Reporting Information [Line Items]
Revenues	26,842	32,092	74,729	102,217	107,371	138,834
Segment net income (loss)	(2,572)	(627)	(4,545)	(1,724)	(4,477)	(2,110)
Natural Gas Operations
Segment Reporting Information [Line Items]
Revenues	255,848	210,834	1,070,576	976,095	1,445,066	1,355,666
Segment net income (loss)	(27,544)	(15,973)	102,584	79,568	182,134	155,993
Natural Gas Operations | Revenues from external customers
Segment Reporting Information [Line Items]
Revenues	255,848	210,834	1,070,576	976,095	1,445,066	1,355,666
Natural Gas Operations | Intersegment revenues
Segment Reporting Information [Line Items]
Revenues	0	0	0	0	0	0
Utility Infrastructure Services
Segment Reporting Information [Line Items]
Revenues	632,848	580,392	1,525,448	1,408,698	2,065,038	1,877,264
Segment net income (loss)	18,540	34,873	32,797	50,936	56,723	66,615
Utility Infrastructure Services | Revenues from external customers
Segment Reporting Information [Line Items]
Revenues	606,006	548,300	1,450,719	1,306,481	1,957,667	1,738,430
Utility Infrastructure Services | Intersegment revenues
Segment Reporting Information [Line Items]
Revenues	$ 26,842	$ 32,092	$ 74,729	$ 102,217	$ 107,371	$ 138,834