Segment Information - Schedule of Reporting Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Revenues	$ 757,247	$ 713,011	$ 1,593,567	$ 1,546,550	$ 3,166,934	$ 3,001,350
Segment net income (loss)	37,965	22,056	110,507	116,865	207,578	198,500
Operating Segments
Segment Reporting Information [Line Items]
Revenues	720,324	663,929	1,523,442	1,458,795	3,025,838	2,837,911
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues	(36,923)	(49,082)	(70,125)	(87,755)	(141,096)	(163,439)
Segment Reconciling Items
Segment Reporting Information [Line Items]
Revenues	0	0	0	0	0	0
Segment net income (loss)	(244)	(231)	(1,097)	(780)	(1,957)	(1,758)
Natural Gas Operations
Segment Reporting Information [Line Items]
Revenues	262,434	258,711	765,261	779,388	1,354,812	1,367,124
Segment net income (loss)	11,942	3,369	95,541	106,758	151,954	152,629
Natural Gas Operations | Operating Segments
Segment Reporting Information [Line Items]
Revenues	262,434	258,711	765,261	779,388	1,354,812	1,367,124
Natural Gas Operations | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues	0	0	0	0	0	0
Utility Infrastructure Services
Segment Reporting Information [Line Items]
Revenues	494,813	454,300	828,306	767,162	1,812,122	1,634,226
Segment net income (loss)	26,267	18,918	16,063	10,887	57,581	47,629
Utility Infrastructure Services | Operating Segments
Segment Reporting Information [Line Items]
Revenues	457,890	405,218	758,181	679,407	1,671,026	1,470,787
Utility Infrastructure Services | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues	$ (36,923)	$ (49,082)	$ (70,125)	$ (87,755)	$ (141,096)	$ (163,439)