Operating Segment, Geographic Information and Significant Customers - Reconciles Net Income (loss), Most Directly Comparable GAAP Financial Measure to Adjusted EBITDA (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting [Abstract]
Income (loss) from continuing operations	$ 2,886	$ (787)	$ 3,603	$ (3,091)
Interest expense, net	4us-gaap_InterestIncomeExpenseNet	8us-gaap_InterestIncomeExpenseNet	9us-gaap_InterestIncomeExpenseNet	22us-gaap_InterestIncomeExpenseNet
Tax provision (benefit)	1,047us-gaap_IncomeTaxExpenseBenefit	(442)us-gaap_IncomeTaxExpenseBenefit	1,047us-gaap_IncomeTaxExpenseBenefit	(1,761)us-gaap_IncomeTaxExpenseBenefit
Depreciation	1,590us-gaap_Depreciation	1,942us-gaap_Depreciation	3,290us-gaap_Depreciation	3,916us-gaap_Depreciation
Amortization of intangible assets	1,762us-gaap_AmortizationOfIntangibleAssets	1,803us-gaap_AmortizationOfIntangibleAssets	3,524us-gaap_AmortizationOfIntangibleAssets	3,788us-gaap_AmortizationOfIntangibleAssets
Restructuring and other charges	1,162us-gaap_RestructuringCharges	97us-gaap_RestructuringCharges	2,430us-gaap_RestructuringCharges	82us-gaap_RestructuringCharges
Stock-based compensation expense	2,256	2,616	4,807	5,604
Adjusted EBITDA	$ 10,707	$ 5,237	$ 18,710	$ 8,560

Operating Segment, Geographic Information and Significant Customers - Reconciles Net Income (loss), Most Directly Comparable GAAP Financial Measure to Adjusted EBITDA (Detail) (USD $)
In Thousands, unless otherwise specified

3 Months Ended

6 Months Ended

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Segment Reporting [Abstract]

Income (loss) from continuing operations

$ 2,886us-gaap_IncomeLossFromContinuingOperations

$ (787)us-gaap_IncomeLossFromContinuingOperations

$ 3,603us-gaap_IncomeLossFromContinuingOperations

$ (3,091)us-gaap_IncomeLossFromContinuingOperations

Interest expense, net

4us-gaap_InterestIncomeExpenseNet

8us-gaap_InterestIncomeExpenseNet

9us-gaap_InterestIncomeExpenseNet

22us-gaap_InterestIncomeExpenseNet

Tax provision (benefit)

1,047us-gaap_IncomeTaxExpenseBenefit

(442)us-gaap_IncomeTaxExpenseBenefit

1,047us-gaap_IncomeTaxExpenseBenefit

(1,761)us-gaap_IncomeTaxExpenseBenefit

Depreciation

1,590us-gaap_Depreciation

1,942us-gaap_Depreciation

3,290us-gaap_Depreciation

3,916us-gaap_Depreciation

Amortization of intangible assets

1,762us-gaap_AmortizationOfIntangibleAssets

1,803us-gaap_AmortizationOfIntangibleAssets

3,524us-gaap_AmortizationOfIntangibleAssets

3,788us-gaap_AmortizationOfIntangibleAssets

Restructuring and other charges

1,162us-gaap_RestructuringCharges

97us-gaap_RestructuringCharges

2,430us-gaap_RestructuringCharges

82us-gaap_RestructuringCharges

Stock-based compensation expense

2,256us-gaap_AllocatedShareBasedCompensationExpense

2,616us-gaap_AllocatedShareBasedCompensationExpense

4,807us-gaap_AllocatedShareBasedCompensationExpense

5,604us-gaap_AllocatedShareBasedCompensationExpense

Adjusted EBITDA

$ 10,707mrcy_AdjustedEarningsBeforeInterestTaxesDepreciationAndAmortization

$ 5,237mrcy_AdjustedEarningsBeforeInterestTaxesDepreciationAndAmortization

$ 18,710mrcy_AdjustedEarningsBeforeInterestTaxesDepreciationAndAmortization

$ 8,560mrcy_AdjustedEarningsBeforeInterestTaxesDepreciationAndAmortization

- Definition

Tabular disclosure of adjusted EBITDA. Adjusted EBITDA is defined as earnings from continuing operations before interest income and expense, income taxes, depreciation, amortization of acquired intangible assets, restructuring, impairment of long-lived assets, acquisition costs and other related expenses, fair value adjustments from purchase accounting and stock-based compensation costs.

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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- Definition

Amount of income (loss) from continuing operations attributable to the parent. Also defined as revenue less expenses and taxes from ongoing operations before extraordinary items but after deduction of those portions of income or loss from continuing operations that are allocable to noncontrolling interests.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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