Operating Segment, Geographic Information and Significant Customers - Geographic Distribution of Revenues and Long Lived Assets from Continuing Operations (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Mar. 31, 2018 USD ($) segment	Mar. 31, 2017 USD ($)	Jun. 30, 2017 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment			1
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	$ 116,336	$ 107,317	$ 340,317	$ 292,980
Identifiable long-lived assets	51,291		51,291		$ 51,643
Components
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	30,022	26,920	102,742	74,126
Modules and Sub-assemblies
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	42,121	43,330	131,581	115,744
Integrated Subsystems
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	44,193	37,067	105,994	103,110
Total Sensor & Effector
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	71,196	76,634	230,574	210,516
Radar
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	37,262	33,017	118,480	115,308
Electronic Warfare
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	19,531	35,920	76,950	78,204
Other Sensor & Effector
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	14,403	7,697	35,144	17,004
C4I
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	26,593	10,242	52,981	21,194
Other End Applications
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	18,547	20,441	56,762	61,270
Domestic
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	94,369	87,765	274,016	244,343
International/Foreign Military Sales
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	21,967	19,552	66,301	48,637
US
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	105,989	98,599	309,391	273,054
Europe
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	8,611	8,085	25,506	14,747
Asia Pacific
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	1,736	633	5,420	5,179
Reportable Geographical Components | US
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	107,610	100,344	315,928	279,979
Identifiable long-lived assets	49,503		49,503		50,340
Reportable Geographical Components | Europe
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	8,846	8,106	25,806	14,783
Identifiable long-lived assets	1,777		1,777		1,288
Reportable Geographical Components | Asia Pacific
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	1,736	633	5,420	5,179
Identifiable long-lived assets	11		11		15
Geography Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	(1,856)	(1,766)	(6,837)	(6,961)
Identifiable long-lived assets	0		0		$ 0
Geography Eliminations | US
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	(1,621)	(1,745)	(6,537)	(6,925)
Geography Eliminations | Europe
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	(235)	(21)	(300)	(36)
Geography Eliminations | Asia Pacific
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	$ 0	$ 0	$ 0	$ 0