Condensed Consolidated Statements of Income (Unaudited) - Parenthetical - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 27, 2018	Jun. 28, 2017	Jun. 27, 2018	Jun. 28, 2017
Income Statement [Abstract]
Interest Income	$ 7	$ 6	$ 15	$ 11

Investment Income, Bank Earning Allowance And Miscellaneous Interest

No definition available.

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