Debt Instrument, Covenant Description, Maximum Leverage Ratio

No definition available.

Name:	loco_DebtInstrumentCovenantDescriptionMaximumLeverageRatio
Namespace Prefix:	loco_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Restrictive Covenants, Maximum Annual Payment For Other Restricted Payments

+ References

No definition available.

+ Details

Name:	loco_DebtInstrumentRestrictiveCovenantsMaximumAnnualPaymentForOtherRestrictedPayments
Namespace Prefix:	loco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Debt Instrument, Restrictive Covenants, Maximum Annual Payment For Stock Option Plans, Employment Agreements and Incentive Plans

+ References

No definition available.

+ Details

Name:	loco_DebtInstrumentRestrictiveCovenantsMaximumAnnualPaymentForStockOptionPlansEmploymentAgreementsandIncentivePlans
Namespace Prefix:	loco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Debt Instrument, Restrictive Covenants, Maximum Annual Redemption, Repurchase, Acquired Equity Interests

+ References

No definition available.

+ Details

Name:	loco_DebtInstrumentRestrictiveCovenantsMaximumAnnualRedemptionRepurchaseAcquiredEquityInterests
Namespace Prefix:	loco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Debt Instrument, Restrictive Covenants, Maximum Annual Repurchase or Redemption of Qualified Entity Interests

+ References

No definition available.

+ Details

Name:	loco_DebtInstrumentRestrictiveCovenantsMaximumAnnualRepurchaseorRedemptionofQualifiedEntityInterests
Namespace Prefix:	loco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

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

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfOperatingSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of restaurants.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfRestaurants
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of stock repurchase plan authorized.

+ References

No definition available.

+ Details

Name:	us-gaap_StockRepurchaseProgramAuthorizedAmount1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Number of shares that have been repurchased during the period and are being held in treasury.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-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

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

- Definition

Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

+ Details

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

- Details

Name:	srt_StatementGeographicalAxis=country_PH
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FranchisorDisclosureAxis=us-gaap_EntityOperatedUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=loco_LosAngelesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FranchisorDisclosureAxis=us-gaap_FranchisedUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=loco_A2018StockRepurchasePlanDomain
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=loco_A2019StockRepurchasePlanDomain
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=loco_CreditAgreementTwoThousandEighteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=loco_ChickenAcquisitionCorpMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Description of Business - Additional Information (Details)		12 Months Ended
	Dec. 11, 2014 USD ($)	Dec. 25, 2019 USD ($) restaurant segment shares	Dec. 26, 2018 USD ($) restaurant shares	Sep. 25, 2019 restaurant	Jun. 26, 2019 restaurant	May 17, 2019 USD ($)	Mar. 27, 2019 restaurant	Sep. 26, 2018 restaurant	Aug. 28, 2018 USD ($)	Jun. 27, 2018 restaurant	Mar. 28, 2018 restaurant
Debt Instrument [Line Items]
Number of restaurants \| restaurant		4	4
Number of operating segments \| segment		1
Value of shares repurchased		$ 48,382,000	$ 981,000
Philippines
Debt Instrument [Line Items]
Number of restaurants \| restaurant		1
Company-operated
Debt Instrument [Line Items]
Number of restaurants \| restaurant		195	213	201	200		211	212		211	212
Company-operated \| The Greater Los Angeles Area
Debt Instrument [Line Items]
Number of restaurants \| restaurant		143
Franchised
Debt Instrument [Line Items]
Number of restaurants \| restaurant		287	271	284	284		273	271		269	268
Franchised \| The Greater Los Angeles Area
Debt Instrument [Line Items]
Number of restaurants \| restaurant		136
2018 Stock Repurchase Plan [Domain]
Debt Instrument [Line Items]
Authorized amount under share repurchase agreement									$ 20,000,000.0
Number of shares repurchased (shares) \| shares		1,558,836	66,409
Value of shares repurchased		$ 18,400,000	$ 1,000,000
2019 Stock Repurchase Plan [Domain]
Debt Instrument [Line Items]
Authorized amount under share repurchase agreement						$ 30,000,000.0
Number of shares repurchased (shares) \| shares		2,836,768
Value of shares repurchased		$ 30,000,000
2018 Credit Agreement
Debt Instrument [Line Items]
Senior secured revolving facility	$ 150,000,000
Senior secured revolving facility term	5 years
Revolving Credit Facility \| 2018 Credit Agreement
Debt Instrument [Line Items]
Maximum annual repurchase or redemption of qualified entity interests		1,000,000
Restrictive covenants, maximum annual repurchase, redemption or acquired equity interests, up to		500,000
Maximum annual payment for stock option plans, employment agreements and incentive plans		2,500,000
Maximum annual payment for other restricted payments		$ 5,000,000
Maximum leverage ratio		4.25
Chicken Acquisition Corp
Debt Instrument [Line Items]
Ownership interest		47.70%