REVENUES FROM CONTRACT WITH CUSTOMERS - Accounting for a Loss Contract (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Jan. 31, 2020	Mar. 24, 2020
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Provision for contract loss	$ 4.1		$ 5.8
TeesREPProject
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Reversal of profit		$ 0.7
Loss recorded	2.7	$ 27.6
Excess of projected project costs over projected project revenues	36.2
The total amounts of accounts receivable and contract assets with the customer	$ 15.5		$ 19.2
Percentage of completion of subcontracted work				90.00%