COSTS AND ESTIMATED EARNINGS ON UNCOMPLETED CONTRACTS (Details Textual) (USD $)	12 Months Ended
	Apr. 30, 2013	Apr. 30, 2012
Increase In Gross Profit	$ 2,054,000
Increase In Gross Profit Per Share	$ 2.07
Decrease In Gross Profit		9,829,000
Decrease In Gross Profit Per Share		$ 9.87
Provision for loss on uncompleted contracts	23,376	1,886,896
Cooper Project [Member]
Increase In Gross Profit	1,641,000
Trenton Operations [Member]
Cumulative-Effect Adjustment, Gross Losses		$ 9,200,000