Business, Basis of Presentation and Significant Accounting Policies - Goodwill and Indefinite-Lived Intangible Assets (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) yr reportingUnit	Dec. 31, 2020 USD ($) yr reportingUnit	Dec. 31, 2019 USD ($) reportingUnit
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Intangible asset, pre-tax impairment charge			$ 3,300
Goodwill	$ 1,520,575	$ 1,243,034	1,221,400
Pre-Qualifications
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Intangible asset, pre-tax impairment charge			3,300
Terminal Growth Rate | Minimum
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, measurement input	0.025	0.025
Terminal Growth Rate | Maximum
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, measurement input	0.030
Number of Years of Discounted Cash Flows | Minimum
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, measurement input | yr	5	5
Number of Years of Discounted Cash Flows | Maximum
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, measurement input | yr	9	9
Discount Rate | Minimum
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, measurement input	0.105	0.130
Discount Rate | Maximum
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, measurement input	0.150	0.150
Goodwill
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Discount rate sensitivity analysis, spread on discount rate for which evaluation was completed (percentage)	1.00%	1.00%
Clean Energy and Infrastructure
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, number of reporting units | reportingUnit	1
Goodwill	$ 166,100	$ 152,700	152,600
Power Delivery
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill	$ 326,800	$ 150,100	$ 149,900
Communications
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, number of reporting units | reportingUnit	3	1	1
Goodwill	$ 601,500	$ 562,100	$ 541,300
Oil and Gas
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, number of reporting units | reportingUnit	4	3	3
Goodwill	$ 426,200	$ 378,100	$ 377,600
Oil and Gas | Reporting Unit A, Quantitative Testing
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, number of reporting units | reportingUnit			1
Oil and Gas | Reporting Unit B, Quantitative Testing
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill			$ 15,000
Goodwill impairment testing, reporting unit, percentage of estimated fair value in excess of carrying value			15.00%