COSTS AND ESTIMATED EARNINGS IN EXCESS OF BILLINGS, NET (Details) - Costs and Estimated Earnings in Excess of Billings, Net - USD ($) $ in Thousands	Oct. 31, 2021	Apr. 30, 2021
Costs and Estimated Earnings in Excess of Billings, Net [Abstract]
Costs and estimated earnings in excess of billings	$ 9,882	$ 12,640
Billings in excess of costs and estimated earnings	(13,361)	(10,692)
Net (liability) asset	$ (3,479)	$ 1,948