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, 2019 USD ($)	Mar. 31, 2018 USD ($)	Mar. 31, 2019 USD ($) segment	Mar. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment			1
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	$ 174,636	$ 116,336	$ 477,781	$ 340,317
Identifiable long-lived assets	55,857		55,857		$ 50,980
Components
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	52,372	30,022	133,686	102,742
Modules and Sub-assemblies
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	36,153	42,121	130,142	131,581
Integrated Subsystems
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	86,111	44,193	213,953	105,994
Total Sensor & Effector
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	105,607	71,196	273,458	230,574
Radar
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	40,674	37,262	123,661	118,480
Electronic Warfare
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	36,569	19,531	86,320	76,950
Other Sensor & Effector
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	28,364	14,403	63,477	35,144
C4I
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	46,217	26,593	137,717	52,981
Other End Applications
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	22,812	18,547	66,606	56,762
Domestic
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	153,634	94,369	427,119	274,016
International/Foreign Military Sales
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	21,002	21,967	50,662	66,301
US
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	158,715	105,989	435,733	309,391
Europe
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	15,280	8,611	39,918	25,506
Asia Pacific
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	641	1,736	2,130	5,420
Reportable Geographical Components | US
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	161,699	107,610	441,167	315,928
Identifiable long-lived assets	51,083		51,083		47,997
Reportable Geographical Components | Europe
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	15,594	8,846	40,935	25,806
Identifiable long-lived assets	4,760		4,760		2,974
Reportable Geographical Components | Asia Pacific
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	641	1,736	2,130	5,420
Identifiable long-lived assets	14		14		9
Geography Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	(3,298)	(1,856)	(6,451)	(6,837)
Identifiable long-lived assets	0		0		$ 0
Geography Eliminations | US
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	2,984	1,621	5,434	6,537
Geography Eliminations | Europe
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	314	235	1,017	300
Geography Eliminations | Asia Pacific
Segment Reporting, Revenue Reconciling Item [Line Items]
Net revenues	$ 0	$ 0	$ 0	$ 0