Segment Information - Summary of segment's internal financial reports (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Contract revenues:	$ 636,624	$ 592,486
Income from operations:	24,902	27,411
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Income from operations:	(15,619)	(15,534)
T&D
Segment Reporting Information [Line Items]
Contract revenues:	364,856	314,908
T&D | Operating Segments
Segment Reporting Information [Line Items]
Income from operations:	30,431	28,673
C&I
Segment Reporting Information [Line Items]
Contract revenues:	271,768	277,578
C&I | Operating Segments
Segment Reporting Information [Line Items]
Income from operations:	$ 10,090	$ 14,272