Segment and Revenue Information - Schedule of Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Segment Reporting Information [Line Items]
Revenue	$ 23,675	$ 42,658	$ 98,561	$ 114,490
Gross profit	3,898	17,225	28,712	44,431
R&D expense	4,513	4,500	13,675	12,567
Operating (loss) income	(7,097)	6,394	(6,912)	13,484
Unallocated expense (income)
Selling, general, and administrative	7,800	6,081	22,550	17,941
Severance	0	0	1,318	0
(Gain) loss on sale of assets	(1,318)	250	(1,919)	439
Gain on extinguishment of debt	0	(6,561)	0	(6,561)
Interest (income) expense, net	(9)	(579)	14	(481)
Foreign exchange (loss) gain	185	(87)	160	(256)
Pension expense	349	0	349	0
Total unallocated expense (income)	7,007	(896)	22,472	11,082
(Loss) income before income tax expense	(7,622)	13,621	(7,435)	20,782
Operating segments
Segment Reporting Information [Line Items]
Revenue	23,675	42,658	98,561	114,490
Operating (loss) income	(615)	12,725	15,037	31,864
Operating segments | Aerospace And Defense
Segment Reporting Information [Line Items]
Revenue	13,416	12,327	32,322	39,097
Gross profit	1,551	3,872	4,468	11,747
R&D expense	3,834	3,598	12,037	10,441
Operating (loss) income	(2,283)	274	(7,569)	1,306
Operating segments | Broadband
Segment Reporting Information [Line Items]
Revenue	10,259	30,331	66,239	75,393
Gross profit	2,347	13,353	24,244	32,684
R&D expense	679	902	1,638	2,126
Operating (loss) income	$ 1,668	$ 12,451	$ 22,606	$ 30,558