Unamortized Deferred Gain (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2012
Property, Plant and Equipment [Abstract]
Current portion	$ 1,157	$ 1,157
Non-current portion	3,242	4,399
Total unamortized deferred gain	$ 4,399	$ 5,556

The current portion of the gain that will be recorded as income or a reduction in rent expense in future periods.

No definition available.

Name:	mrcy_SaleLeasebackTransactionDeferredGainCurrentPortion
Namespace Prefix:	mrcy_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant