Segment Data and Related Information (Schedule of Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Revenue	$ 33,426	$ 25,482
Gross profit	12,572	7,474
R&D expense	4,296	4,642
Operating income (loss)	2,507	(1,453)
Unallocated (income) expense:
Selling, general, and administrative	5,798	5,887
Gain on sale of assets	(29)	(1,602)
Interest expense, net	49	15
Foreign exchange gain	(237)	(147)
Total unallocated expense	5,581	4,153
Income (loss) before income tax expense	2,695	(1,321)
Operating segments
Segment Reporting Information [Line Items]
Revenue	33,426	25,482
Operating income (loss)	8,276	2,832
Operating segments | Aerospace And Defense
Segment Reporting Information [Line Items]
Revenue	13,636	13,704
Gross profit	4,100	4,488
R&D expense	3,686	3,951
Operating income (loss)	414	537
Operating segments | Broadband
Segment Reporting Information [Line Items]
Revenue	19,790	11,778
Gross profit	8,472	2,987
R&D expense	610	692
Operating income (loss)	$ 7,862	$ 2,295