For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Revenue from Contracts with Customers - Revenues Disaggregated by Geographic Market (Details) - Revenue - Geographic Concentration Risk	12 Months Ended
	Dec. 26, 2018	Dec. 27, 2017	Dec. 28, 2016
Disaggregation of Revenue [Line Items]
Percentage of concentration	100.00%
Greater Los Angeles area market
Disaggregation of Revenue [Line Items]
Percentage of concentration	69.20%	73.00%	75.00%
Other markets
Disaggregation of Revenue [Line Items]
Percentage of concentration	30.80%