Segment Information (Details) - Reconciliation of Operating Profit (Loss) from Segments to Consolidated - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2021	Apr. 30, 2020
Operating (loss) income:
Operating profit (loss)	$ (958)	$ (10,922)
Frequency Electronics Inc New York [Member]
Operating (loss) income:
Operating profit (loss)	(1,067)	(9,910)
Frequency Electronics Inc Zyfer [Member]
Operating (loss) income:
Operating profit (loss)	655	(673)
Inter Segment [Member]
Operating (loss) income:
Operating profit (loss)	(204)	0
Corporate Segment [Member]
Operating (loss) income:
Operating profit (loss)	$ (342)	$ (339)