Property and Equipment - Unamortized Deferred Gain (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Jun. 30, 2014
Property, Plant and Equipment [Abstract]
Current portion	$ 1,156	$ 1,156
Non-current portion	929	2,086
Total unamortized deferred gain	$ 2,085	$ 3,242

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