Fair Value Measurements - Investments (Details) - USD ($) $ in Thousands	Jul. 02, 2016	Apr. 02, 2016
Available for sale Securities Current
Schedule of Available-for-sale Securities
Cost	$ 20,388	$ 26,384
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	2	5
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0	0
Available-for-sale Securities	20,390	26,389
Available for sale Securities Current \| Commercial Paper
Schedule of Available-for-sale Securities
Cost	18,437	13,137
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	0	0
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0	0
Available-for-sale Securities	18,437	13,137
Available for sale Securities Current \| US Government Agencies Debt Securities [Member]
Schedule of Available-for-sale Securities
Cost	1,951	13,247
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	2	5
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0	0
Available-for-sale Securities	1,953	13,252
Available For Sale Securities Non Current [Member]
Schedule of Available-for-sale Securities
Cost	2,740	2,507
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	50	0
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0	3
Available-for-sale Securities	2,790	2,504
Available For Sale Securities Non Current [Member] \| Exchange traded funds and money market securities [Member]
Schedule of Available-for-sale Securities
Cost	2,740	2,507
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	50	0
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0	3
Available-for-sale Securities	$ 2,790	$ 2,504

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

+ Details

Name:	us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

+ Details

Name:	us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=51813488&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49167202&loc=d3e26610-111562

+ Details

Name:	us-gaap_AvailableForSaleSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ 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 210.5-02.2)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesAmortizedCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	invest_InvestmentAxis=esio_AvailableForSaleSecuritiesCurrentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	invest_InvestmentAxis=esio_AvailableForSaleSecuritiesNonCurrentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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