Revenue from Contracts with Customers - Revenues Disaggregated by Geographic Market (Details) - Revenue - Geographic Concentration Risk	3 Months Ended
Mar. 31, 2021	Mar. 25, 2020
Disaggregation of Revenue [Line Items]
Percentage of concentration	100.00%	100.00%
Greater Los Angeles area market
Disaggregation of Revenue [Line Items]
Percentage of concentration	70.10%	72.40%
Other markets
Disaggregation of Revenue [Line Items]
Percentage of concentration	29.90%	27.60%

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://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
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