Background, Organization, and Summary of Significant Accounting Policies - Schedule of Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021 USD ($)
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 345,184
Additional goodwill from Riggs Distler acquisition	446,794
Foreign currency translation adjustment	(76)
Goodwill, ending balance	791,902
Natural Gas Operations
Goodwill [Roll Forward]
Goodwill, beginning balance	10,095
Additional goodwill from Riggs Distler acquisition	0
Foreign currency translation adjustment	0
Goodwill, ending balance	10,095
Utility Infrastructure Services
Goodwill [Roll Forward]
Goodwill, beginning balance	335,089
Additional goodwill from Riggs Distler acquisition	446,794
Foreign currency translation adjustment	(76)
Goodwill, ending balance	$ 781,807