14. Segment Information (Details) - Reconciliation of Operating Profit (Loss) from Segments to Consolidated - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Operating loss:
Operating profit (loss)	$ (2,817)	$ (12,395)
Frequency Electronics Inc New York [Member]
Operating loss:
Operating profit (loss)	(4,429)	(15,097)
Frequency Electronics Inc Zyfer [Member]
Operating loss:
Operating profit (loss)	1,730	3,164
Corporate Segment [Member]
Operating loss:
Operating profit (loss)	$ (118)	$ (462)