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

No definition available.

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

- Definition

Significant Accounting Policies [Line Items]

+ References

No definition available.

+ Details

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Namespace Prefix:	mrcy_
Data Type:	xbrli:stringItemType
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- Definition

Face amount or stated value per share of common stock.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of common stock allocated to investors to buy shares of a new issue of common stock before they are offered to the public. When stock is sold on a subscription basis, the issuer does not initially receive the total proceeds. In general, the issuer does not issue the shares to the investor until it receives the entire proceeds.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Cash received on stock transaction after deduction of issuance costs.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The number of shares issued or sold by the subsidiary or equity method investee per stock transaction.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Per share or per unit amount of equity securities issued.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_DeferredRevenueArrangementTypeAxis=mrcy_MultipleDeliveryRevenueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsidiarySaleOfStockAxis=us-gaap_OverAllotmentOptionMember
Namespace Prefix:
Data Type:	na
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Period Type:

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended		9 Months Ended
	Feb. 01, 2017	May 02, 2016	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016	Jan. 26, 2017	Jun. 30, 2016
Significant Accounting Policies [Line Items]
Common stock, shares subscribed but unissued							6,000,000
Common stock, par value (usd per share)			$ 0.01		$ 0.01		$ 0.01	$ 0.01
Shares issued, price per share (usd per share)							$ 33.00
Multiple Delivery Revenue [Member]
Significant Accounting Policies [Line Items]
Percentage Of Revenue Recognized			37.00%	39.00%	32.00%	41.00%
Over-Allotment Option [Member]
Significant Accounting Policies [Line Items]
Common stock, shares subscribed but unissued							900,000
Number of shares issued in transaction	6,900,000
Shares issued in transaction	$ 215,732	$ 92,788