Expenses by Reportable Segment for Restructuring Plans (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2013		Jun. 30, 2012
Component of Operating Other Cost and Expense [Line Items]
Restructuring charges, provisions	$ 228	$ 5,429		$ 2,821
Cash paid		(7,479)		(123)
Reversals		(458)	[1]
Restructuring liability at end period	648	648		2,698
Severance
Component of Operating Other Cost and Expense [Line Items]
Restructuring charges, provisions				2,515
Cash paid		(7,171)		(2)
Reversals		(458)	[1]
Restructuring liability at end period	362	362		2,513
Facilities And Other
Component of Operating Other Cost and Expense [Line Items]
Restructuring charges, provisions				306
Cash paid		(308)		(121)
Restructuring liability at end period	286	286		185
Mercury Commercial Electronics
Component of Operating Other Cost and Expense [Line Items]
Restructuring charges, provisions		5,887
Restructuring charges, provisions				2,712
Mercury Commercial Electronics | Severance
Component of Operating Other Cost and Expense [Line Items]
Restructuring charges, provisions		5,478
Restructuring charges, provisions				2,406
Mercury Commercial Electronics | Facilities And Other
Component of Operating Other Cost and Expense [Line Items]
Restructuring charges, provisions		409
Restructuring charges, provisions				306
Mercury Defense and Intelligence Systems
Component of Operating Other Cost and Expense [Line Items]
Restructuring charges, provisions				109
Mercury Defense and Intelligence Systems | Severance
Component of Operating Other Cost and Expense [Line Items]
Restructuring charges, provisions				$ 109

[1] Reversals result from the finalization of severance agreements and unused outplacement services.