CUSTOMER CONCENTRATIONS (Details) $ in Millions		1 Months Ended		3 Months Ended
	Jan. 31, 2019 USD ($)	Apr. 30, 2019 USD ($)	Apr. 30, 2018	Apr. 30, 2019 USD ($) customer	Apr. 30, 2018 customer
Customer Concentrations
Amounts retained by project owners | $	$ 15.3	$ 15.9		$ 15.9
Major Customer One | Accounts Receivable
Customer Concentrations
Percentage of consolidated accounts receivable accounted by major customer	25.00%	15.00%
Major Customer Two | Revenue
Customer Concentrations
Percentage of major customers or segments		14.00%
Major Customer Two | Accounts Receivable
Customer Concentrations
Percentage of consolidated accounts receivable accounted by major customer	15.00%	12.00%
Power Services | Revenue
Customer Concentrations
Percentage of major customers or segments		41.00%			87.00%
Number of major power industry service customers | customer				2	4
Power Services | Major Customer One | Revenue
Customer Concentrations
Percentage of major customers or segments		17.00%	22.00%
Power Services | Major Customer Two | Revenue
Customer Concentrations
Percentage of major customers or segments			19.00%
Power Services | Major Customer Three | Revenue
Customer Concentrations
Percentage of major customers or segments			12.00%
Power Services | Major Customer Four | Revenue
Customer Concentrations
Percentage of major customers or segments			12.00%
Industry services | Revenue
Customer Concentrations
Percentage of major customers or segments		55.00%	12.00%