Goodwill Goodwill - Changes in Carrying Amount of Goodwill (Detail) $ in Thousands	12 Months Ended
	Jun. 30, 2018 USD ($)
Goodwill [Roll Forward]
Beginning Balance	$ 380,846
Ending Balance	497,442
Sensor And Mission Processing [Member]
Goodwill [Roll Forward]
Beginning Balance	116,003
Ending Balance	119,560
AMS [Member]
Goodwill [Roll Forward]
Beginning Balance	217,956
Ending Balance	218,147
MDS
Goodwill [Roll Forward]
Beginning Balance	46,887
Ending Balance	159,735
CES Creative Electronic Systems S.A. [Member]
Goodwill [Roll Forward]
Goodwill adjustments	291
CES Creative Electronic Systems S.A. [Member] | Sensor And Mission Processing [Member]
Goodwill [Roll Forward]
Goodwill adjustments	291
CES Creative Electronic Systems S.A. [Member] | AMS [Member]
Goodwill [Roll Forward]
Goodwill adjustments	0
CES Creative Electronic Systems S.A. [Member] | MDS
Goodwill [Roll Forward]
Goodwill adjustments	0
Delta
Goodwill [Roll Forward]
Goodwill adjustments	191
Delta | Sensor And Mission Processing [Member]
Goodwill [Roll Forward]
Goodwill adjustments	0
Delta | AMS [Member]
Goodwill [Roll Forward]
Goodwill adjustments	191
Delta | MDS
Goodwill [Roll Forward]
Goodwill adjustments	0
RTL
Goodwill [Roll Forward]
Goodwill arising from acquisition	3,266
RTL | Sensor And Mission Processing [Member]
Goodwill [Roll Forward]
Goodwill arising from acquisition	3,266
RTL | AMS [Member]
Goodwill [Roll Forward]
Goodwill arising from acquisition	0
RTL | MDS
Goodwill [Roll Forward]
Goodwill arising from acquisition	0
Themis
Goodwill [Roll Forward]
Goodwill arising from acquisition	112,848
Themis | Sensor And Mission Processing [Member]
Goodwill [Roll Forward]
Goodwill arising from acquisition	0
Themis | AMS [Member]
Goodwill [Roll Forward]
Goodwill arising from acquisition	0
Themis | MDS
Goodwill [Roll Forward]
Goodwill arising from acquisition	$ 112,848