Revenue - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Disaggregation of Revenue [Line Items]
Revenues	$ 311,740	$ 286,273	$ 859,539	$ 806,335
Oil and gas (excludes petrochemical)
Disaggregation of Revenue [Line Items]
Revenues	106,275	105,464	316,908	302,310
Electric utility
Disaggregation of Revenue [Line Items]
Revenues	88,616	74,909	238,368	196,488
Commercial and other industrial
Disaggregation of Revenue [Line Items]
Revenues	76,317	49,519	171,388	134,188
Petrochemical
Disaggregation of Revenue [Line Items]
Revenues	18,461	36,349	68,790	113,236
Light rail traction power
Disaggregation of Revenue [Line Items]
Revenues	7,961	8,549	25,623	26,785
All others
Disaggregation of Revenue [Line Items]
Revenues	14,110	11,483	38,462	33,328
United States
Disaggregation of Revenue [Line Items]
Revenues	250,624	224,537	677,774	650,143
Canada
Disaggregation of Revenue [Line Items]
Revenues	24,140	42,611	86,422	108,275
Middle East and Africa
Disaggregation of Revenue [Line Items]
Revenues	15,875	9,917	39,365	22,757
Europe
Disaggregation of Revenue [Line Items]
Revenues	8,606	5,522	27,310	16,947
Asia/Pacific
Disaggregation of Revenue [Line Items]
Revenues	11,782	1,805	26,925	5,031
Mexico, Central and South America
Disaggregation of Revenue [Line Items]
Revenues	$ 713	$ 1,881	$ 1,743	$ 3,182