Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Revenues	$ 194,017	$ 126,858
Oil and gas (excludes petrochemical)
Disaggregation of Revenue [Line Items]
Revenues	83,636	43,510
Petrochemical
Disaggregation of Revenue [Line Items]
Revenues	28,367	22,490
Electric utility
Disaggregation of Revenue [Line Items]
Revenues	40,703	28,407
Commercial and other industrial
Disaggregation of Revenue [Line Items]
Revenues	24,672	17,050
Traction power
Disaggregation of Revenue [Line Items]
Revenues	4,345	7,072
All others
Disaggregation of Revenue [Line Items]
Revenues	12,294	8,329
United States
Disaggregation of Revenue [Line Items]
Revenues	159,860	100,112
Canada
Disaggregation of Revenue [Line Items]
Revenues	20,350	18,496
Europe
Disaggregation of Revenue [Line Items]
Revenues	6,532	4,134
Middle East and Africa
Disaggregation of Revenue [Line Items]
Revenues	3,275	2,425
Mexico, Central and South America
Disaggregation of Revenue [Line Items]
Revenues	2,657	915
Asia/Pacific
Disaggregation of Revenue [Line Items]
Revenues	$ 1,343	$ 776