14. Segment Information (Details) - Schedule of Reconciliation of Depreciation and Amortization from Segment to Consolidated - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Depreciation and amortization (allocated):
Depreciation and Amortization	$ 2,638	$ 2,498
Frequency Electronics Inc New York [Member]
Depreciation and amortization (allocated):
Depreciation and Amortization	2,471	2,323
Frequency Electronics Inc Zyfer [Member]
Depreciation and amortization (allocated):
Depreciation and Amortization	152	160
Corporate Segment [Member]
Depreciation and amortization (allocated):
Depreciation and Amortization	$ 15	$ 15