Business Segment Data - Summary of Segment Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Total assets	$ 1,279,292	$ 1,110,582
Operating segments
Segment Reporting Information [Line Items]
Total assets	1,255,341	1,089,471
Operating segments | Electrical & Mechanical
Segment Reporting Information [Line Items]
Total assets	828,937	712,691
Operating segments | Transmission & Distribution
Segment Reporting Information [Line Items]
Total assets	426,404	376,780
Other reconciling items
Segment Reporting Information [Line Items]
Total assets	44,832	43,628
Eliminations
Segment Reporting Information [Line Items]
Total assets	$ (20,881)	$ (22,517)