Operating Segment, Geographic Information and Significant Customers - Geographic Distribution of Revenues and Long Lived Assets from Continuing Operations (Detail) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) segment	Dec. 31, 2016 USD ($)	Jun. 30, 2017 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment			1
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	$ 117,912	$ 98,014	$ 223,981	$ 185,663
Identifiable long-lived assets	51,640		51,640		$ 51,643
Components
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	39,908	24,636	72,720	44,468
Modules and Sub-assemblies
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	41,728	38,560	89,460	75,152
Integrated Subsystems
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	36,276	34,818	61,801	66,043
Total Sensor & Effector
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	85,081	70,768	159,378	133,883
Radar
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	44,678	44,803	81,218	82,292
Electronic Warfare
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	29,411	21,304	57,419	42,284
Other Sensor & Effector
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	10,992	4,661	20,741	9,307
C4I
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	13,562	6,613	26,388	10,953
Other End Applications
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	19,269	20,633	38,215	40,827
Domestic
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	89,969	83,052	179,647	156,578
International/Foreign Military Sales
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	27,943	14,962	44,334	29,085
US
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	105,687	91,407	203,402	174,455
Europe
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	9,417	5,809	16,895	6,662
Asia Pacific
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	2,808	798	3,684	4,546
Reportable Geographical Components | US
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	108,856	93,300	208,318	179,635
Identifiable long-lived assets	50,305		50,305		50,340
Reportable Geographical Components | Europe
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	9,460	5,809	16,960	6,677
Identifiable long-lived assets	1,323		1,323		1,288
Reportable Geographical Components | Asia Pacific
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	2,808	798	3,684	4,546
Identifiable long-lived assets	12		12		15
Geography Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	(3,212)	(1,893)	(4,981)	(5,195)
Identifiable long-lived assets	0		0		$ 0
Geography Eliminations | US
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	(3,169)	(1,893)	(4,916)	(5,180)
Geography Eliminations | Europe
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	(43)	0	(65)	(15)
Geography Eliminations | Asia Pacific
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	$ 0	$ 0	$ 0	$ 0