Investment Maturity, Period

No definition available.

Name:	extr_InvestmentMaturityPeriod
Namespace Prefix:	extr_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Limited lifetime hardware warranty, maximum period following end of product sales.

+ References

No definition available.

+ Details

Name:	extr_LimitedLifetimeHardwareWarrantyMaximumPeriodFollowingEndOfProductSales
Namespace Prefix:	extr_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Minimum percentage of tax benefit realized upon settlement.

+ References

No definition available.

+ Details

Name:	extr_MinimumPercentageOfTaxBenefitRealizedUponSettlement
Namespace Prefix:	extr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Significant Accounting Policies [Line Items]

+ References

No definition available.

+ Details

Name:	extr_SignificantAccountingPoliciesLineItems
Namespace Prefix:	extr_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Standard hardware warranty, period.

+ References

No definition available.

+ Details

Name:	extr_StandardHardwareWarrantyPeriod
Namespace Prefix:	extr_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Standard software warranty, period.

+ References

No definition available.

+ Details

Name:	extr_StandardSoftwareWarrantyPeriod
Namespace Prefix:	extr_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount charged to advertising expense for the period, which are expenses incurred with the objective of increasing revenue for a specified brand, product or product line.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 720
-SubTopic 35
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6420018&loc=d3e36677-107848

+ Details

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

- Definition

Amount of the cumulative effect on retained earnings net of related income tax effect.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22663-107794

+ Details

Name:	us-gaap_CumulativeEffectOnRetainedEarningsNetOfTax1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Total loss recognized during the period from the impairment of goodwill plus the loss recognized in the period resulting from the impairment of the carrying amount of intangible assets, other than goodwill.

+ References

No definition available.

+ Details

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

- Definition

Amount after tax, before reclassification adjustments, of unrealized holding gain (loss) on available-for-sale securities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669646-108580

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e637-108580

+ Details

Name:	us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201601Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_ComputerSoftwareIntangibleAssetMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_ComputerEquipmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_OfficeEquipmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_LeaseholdImprovementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_CashEquivalentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_ShortTermInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Summary of Significant Accounting Policies (Narratives) (Details) - USD ($)			12 Months Ended
	Jul. 01, 2018	Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016
Significant Accounting Policies [Line Items]
Intangible asset and goodwill impairment			$ 0	$ 0
Standard hardware warranty period (in months)			12 months
Standard software warranty period (in days)			90 days
Limited lifetime hardware warranty maximum period after end of sale of product (in years)			5 years
Advertising expenses			$ 500,000	$ 400,000	$ 300,000
Minimum percentage of tax benefit realized upon settlement		50.00%	50.00%
Unrealized holding gain, net of tax			$ 497,000
ASU 2016-01
Significant Accounting Policies [Line Items]
Unrealized holding gain, net of tax		$ 500,000
ASU 2016-01 \| Subsequent Event
Significant Accounting Policies [Line Items]
Adjustment to accumulated deficit	$ 500,000
Maximum \| Purchased Software
Significant Accounting Policies [Line Items]
Estimated useful lives of property and equipment			4 years
Maximum \| Computer Equipment
Significant Accounting Policies [Line Items]
Estimated useful lives of property and equipment			4 years
Maximum \| Office Equipment
Significant Accounting Policies [Line Items]
Estimated useful lives of property and equipment			7 years
Maximum \| Leasehold Improvements
Significant Accounting Policies [Line Items]
Estimated useful lives of property and equipment			10 years
Minimum \| Purchased Software
Significant Accounting Policies [Line Items]
Estimated useful lives of property and equipment			1 year
Minimum \| Computer Equipment
Significant Accounting Policies [Line Items]
Estimated useful lives of property and equipment			1 year
Minimum \| Office Equipment
Significant Accounting Policies [Line Items]
Estimated useful lives of property and equipment			3 years
Minimum \| Leasehold Improvements
Significant Accounting Policies [Line Items]
Estimated useful lives of property and equipment			2 years
Cash equivalents \| Maximum
Significant Accounting Policies [Line Items]
Maturity period for investments			3 months
Short-term Investments \| Maximum
Significant Accounting Policies [Line Items]
Maturity period for investments			1 year
Short-term Investments \| Minimum
Significant Accounting Policies [Line Items]
Maturity period for investments			3 months