Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue [Line Items]
Revenues	$ 255,108	$ 171,444	$ 449,125	$ 298,302
Oil and gas (excludes petrochemical)
Disaggregation of Revenue [Line Items]
Revenues	103,820	62,597	187,456	106,107
Petrochemical
Disaggregation of Revenue [Line Items]
Revenues	50,070	25,887	78,437	48,377
Electric utility
Disaggregation of Revenue [Line Items]
Revenues	47,502	42,668	88,205	71,075
Commercial and other industrial
Disaggregation of Revenue [Line Items]
Revenues	34,894	22,270	59,566	39,320
Light rail traction power
Disaggregation of Revenue [Line Items]
Revenues	4,517	7,317	8,862	14,389
All others
Disaggregation of Revenue [Line Items]
Revenues	14,305	10,705	26,599	19,034
United States
Disaggregation of Revenue [Line Items]
Revenues	216,933	134,161	376,793	234,273
Canada
Disaggregation of Revenue [Line Items]
Revenues	24,160	21,995	44,510	40,491
Europe
Disaggregation of Revenue [Line Items]
Revenues	8,265	7,953	14,797	12,087
Middle East and Africa
Disaggregation of Revenue [Line Items]
Revenues	2,803	4,004	6,078	6,429
Mexico, Central and South America
Disaggregation of Revenue [Line Items]
Revenues	2,159	1,543	4,816	2,458
Asia/Pacific
Disaggregation of Revenue [Line Items]
Revenues	$ 788	$ 1,788	$ 2,131	$ 2,564