Debt Instrument, Periodic Payment On New Borrowings

No definition available.

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Namespace Prefix:	loco_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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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

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Amount of the required periodic payments including both interest and principal payments.

+ 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 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of the required periodic payments applied to principal.

+ References

+ Details

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

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

+ Details

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

- Definition

The effective interest rate during the reporting period.

+ References

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- 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

+ Details

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

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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

- Definition

The carrying value as of the balance sheet date of the noncurrent portion of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ 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 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section 45
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=99376301&loc=d3e1336-112600

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section 45
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=99376301&loc=d3e1314-112600

+ Details

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

- Details

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- Details

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- Details

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- Details

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- Details

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Credit Agreements - Additional Information (Details) - USD ($)			3 Months Ended		9 Months Ended
	Jul. 13, 2018	Dec. 11, 2014	Sep. 26, 2018	Sep. 27, 2017	Sep. 26, 2018	Sep. 27, 2017	Dec. 27, 2017
Debt Instrument [Line Items]
Revolver loan			$ 71,000,000		$ 71,000,000		$ 93,000,000
Senior Secured Revolving Credit Facility \| 2014 Revolver
Debt Instrument [Line Items]
Senior secured revolving facility		$ 200,000,000
Senior secured revolving facility term		5 years
Revolving credit facility maturity period					Jul. 13, 2023
Letters of credit outstanding			7,700,000		$ 7,700,000
Revolver loan			71,000,000		71,000,000
Amount of borrowings available			71,300,000		71,300,000
Gross payments on outstanding borrowings			10,000,000	$ 9,500,000		$ 19,000,000
Payments made on new borrowings			$ 6,000,000
Senior Secured Revolving Credit Facility \| 2014 Revolver \| Letter of Credit
Debt Instrument [Line Items]
Sub limit of revolving facility		$ 15,000,000
Senior Secured Revolving Credit Facility \| 2014 Revolver \| Swing Line Loans
Debt Instrument [Line Items]
Sub limit of revolving facility		$ 15,000,000
Senior Secured Revolving Credit Facility \| Credit Agreement Two Thousand Eighteen
Debt Instrument [Line Items]
Senior secured revolving facility	$ 150,000,000
Senior secured revolving facility term	5 years
Debt instrument basis percentage			1.00%
Gross payments on outstanding borrowings					13,000,000
Principal payments prior to maturity					$ 0
Senior Secured Revolving Credit Facility \| Credit Agreement Two Thousand Eighteen \| Minimum
Debt Instrument [Line Items]
Debt instrument, interest rate			3.60%	3.00%	3.30%	2.40%
Senior Secured Revolving Credit Facility \| Credit Agreement Two Thousand Eighteen \| Maximum
Debt Instrument [Line Items]
Debt instrument, interest rate			3.80%	3.00%	3.80%	3.00%
Senior Secured Revolving Credit Facility \| Credit Agreement Two Thousand Eighteen \| Federal Funds Rate
Debt Instrument [Line Items]
Debt instrument basis percentage			0.50%
Senior Secured Revolving Credit Facility \| Credit Agreement Two Thousand Eighteen \| LIBOR \| Minimum
Debt Instrument [Line Items]
Debt instrument basis percentage			1.25%
Senior Secured Revolving Credit Facility \| Credit Agreement Two Thousand Eighteen \| LIBOR \| Maximum
Debt Instrument [Line Items]
Debt instrument basis percentage			2.25%
Senior Secured Revolving Credit Facility \| Credit Agreement Two Thousand Eighteen \| Base Rate \| Minimum
Debt Instrument [Line Items]
Debt instrument basis percentage			0.25%
Senior Secured Revolving Credit Facility \| Credit Agreement Two Thousand Eighteen \| Base Rate \| Maximum
Debt Instrument [Line Items]
Debt instrument basis percentage			1.25%
Senior Secured Revolving Credit Facility \| Credit Agreement Two Thousand Eighteen \| Letter of Credit
Debt Instrument [Line Items]
Sub limit of revolving facility	$ 15,000,000
Senior Secured Revolving Credit Facility \| Credit Agreement Two Thousand Eighteen \| Swing Line Loans
Debt Instrument [Line Items]
Sub limit of revolving facility	$ 15,000,000