REVENUE - Liability Balance (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 24, 2020	Jun. 26, 2019	Jun. 24, 2020	Jun. 26, 2019
Revenue from Contract with Customer [Abstract]
Gift card liability	$ 46	$ 105	$ 345	$ 383
Deferred revenue	$ 134	$ 85	$ 305	$ 219

Amount of increase (decrease) in obligation to transfer good or service to customer for which consideration has been received or is receivable.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

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