Description of Business (Details)	6 Months Ended
Dec. 27, 2019 program
Accounting Policies [Abstract]
Number of programs using products and services	300
Percentage of revenue recognized	77.00%

Percentage of total revenue recognized under multiple-deliverable arrangements during the reporting periods.

No definition available.

Name:	mrcy_PercentageOfRevenueRecognized
Namespace Prefix:	mrcy_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration