Background, Organization, and Summary of Significant Accounting Policies - Schedule of Goodwill (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 359,045
Foreign currency translation adjustment	2,134
Goodwill, ending balance	364,482
Natural Gas Operations
Goodwill [Roll Forward]
Goodwill, beginning balance	10,095
Foreign currency translation adjustment	0
Goodwill, ending balance	10,095
Utility Infrastructure Services
Goodwill [Roll Forward]
Goodwill, beginning balance	348,950
Foreign currency translation adjustment	2,134
Goodwill, ending balance	354,387
Linetec
Goodwill [Roll Forward]
Measurement Period Adjustment - Linetec acquisition	3,303
Goodwill, ending balance	191,800
Linetec | Natural Gas Operations
Goodwill [Roll Forward]
Measurement Period Adjustment - Linetec acquisition	0
Linetec | Utility Infrastructure Services
Goodwill [Roll Forward]
Measurement Period Adjustment - Linetec acquisition	$ 3,303