Goodwill and Other Intangible Assets - Summary of Changes in Goodwill (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Goodwill gross, beginning balance		$ 1,996,362,000	$ 1,966,432,000	$ 1,642,902,000
Accumulated impairment, beginning balance		(96,483,000)	(97,832,000)	(39,733,000)
Goodwill net, beginning balance		1,899,879,000	1,868,600,000	1,603,169,000
Goodwill acquired		110,383,000	56,337,000	302,408,000
Purchase price allocation adjustments		1,503,000	51,000	(1,278,000)
Goodwill impairment	$ 0		0	(57,011,000)
Foreign currency translation adjustments		10,910,000	(25,109,000)	21,312,000
Goodwill gross, ending balance	2,119,101,000	2,119,101,000	1,996,362,000	1,966,432,000
Accumulated impairment, ending balance	(96,426,000)	(96,426,000)	(96,483,000)	(97,832,000)
Goodwill net, ending balance	2,022,675,000	2,022,675,000	1,899,879,000	1,868,600,000
Electric Power Infrastructure Services Division
Goodwill [Roll Forward]
Goodwill gross, beginning balance		1,313,078,000	1,272,527,000	1,253,979,000
Accumulated impairment, beginning balance		0	0	0
Goodwill net, beginning balance		1,313,078,000	1,272,527,000	1,253,979,000
Goodwill acquired		43,183,000	56,337,000	5,866,000
Purchase price allocation adjustments		1,503,000	51,000	(619,000)
Goodwill impairment				0
Foreign currency translation adjustments		7,399,000	(15,837,000)	13,301,000
Goodwill gross, ending balance	1,365,163,000	1,365,163,000	1,313,078,000	1,272,527,000
Accumulated impairment, ending balance	0	0	0	0
Goodwill net, ending balance	1,365,163,000	1,365,163,000	1,313,078,000	1,272,527,000
Pipeline and Industrial Infrastructure Services Division
Goodwill [Roll Forward]
Goodwill gross, beginning balance		683,284,000	693,905,000	388,923,000
Accumulated impairment, beginning balance		(96,483,000)	(97,832,000)	(39,733,000)
Goodwill net, beginning balance		586,801,000	596,073,000	349,190,000
Goodwill acquired		67,200,000	0	296,542,000
Purchase price allocation adjustments		0	0	(659,000)
Goodwill impairment				(57,011,000)
Foreign currency translation adjustments		3,511,000	(9,272,000)	8,011,000
Goodwill gross, ending balance	753,938,000	753,938,000	683,284,000	693,905,000
Accumulated impairment, ending balance	(96,426,000)	(96,426,000)	(96,483,000)	(97,832,000)
Goodwill net, ending balance	$ 657,512,000	$ 657,512,000	$ 586,801,000	$ 596,073,000