Acquisitions, Goodwill and Other Intangible Assets - Rollforward of Goodwill by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Goodwill, gross	$ 1,645,300		$ 1,342,900
Accumulated impairment loss	(124,700)		(121,500)
Goodwill, net	1,520,575	$ 1,243,034	1,221,400
Goodwill [Roll Forward]
Goodwill, net, beginning balance	1,243,034	1,221,400
Additions from new business combinations	277,300	15,100
Measurement period adjustments, net	100	6,100
Currency translation adjustments	200	400
Goodwill, net, ending balance	1,520,575	1,243,034	1,221,400
Communications
Goodwill [Line Items]
Goodwill, gross	601,500		541,300
Accumulated impairment loss	0		0
Goodwill, net	601,500	562,100	541,300
Goodwill [Roll Forward]
Goodwill, net, beginning balance	562,100	541,300
Additions from new business combinations	39,300	14,900
Measurement period adjustments, net	100	5,900
Currency translation adjustments	0	0
Goodwill, net, ending balance	601,500	562,100	541,300
Clean Energy and Infrastructure
Goodwill [Line Items]
Goodwill, gross	166,100		152,600
Accumulated impairment loss	0		0
Goodwill, net	166,100	152,700	152,600
Goodwill [Roll Forward]
Goodwill, net, beginning balance	152,700	152,600
Additions from new business combinations	13,400	0
Measurement period adjustments, net	0	100
Currency translation adjustments	0	0
Goodwill, net, ending balance	166,100	152,700	152,600
Oil and Gas
Goodwill [Line Items]
Goodwill, gross	550,900		499,100
Accumulated impairment loss	(124,700)		(121,500)
Goodwill, net	426,200	378,100	377,600
Goodwill [Roll Forward]
Goodwill, net, beginning balance	378,100	377,600
Additions from new business combinations	47,900	0
Measurement period adjustments, net	0	100
Currency translation adjustments	200	400
Goodwill, net, ending balance	426,200	378,100	377,600
Power Delivery
Goodwill [Line Items]
Goodwill, gross	326,800		149,900
Accumulated impairment loss	0		0
Goodwill, net	326,800	150,100	149,900
Goodwill [Roll Forward]
Goodwill, net, beginning balance	150,100	149,900
Additions from new business combinations	176,700	200
Measurement period adjustments, net	0	0
Currency translation adjustments	0	0
Goodwill, net, ending balance	$ 326,800	$ 150,100	$ 149,900