Contract Liabilities - Performance Obligations (Details)	Jun. 29, 2019 USD ($)
Contract Liabilities:
Revenue, remaining peformance obligation	$ 9,819,400
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-06-30
Contract Liabilities:
Revenue, remaining peformance obligation	$ 849,700
Future estimated revenue to be recognised related to performance obligations
Duration of expected recognition period for remaining performance obligation	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-12-29
Contract Liabilities:
Revenue, remaining peformance obligation	$ 1,657,800
Future estimated revenue to be recognised related to performance obligations
Duration of expected recognition period for remaining performance obligation	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-12-27
Contract Liabilities:
Revenue, remaining peformance obligation	$ 1,519,000
Future estimated revenue to be recognised related to performance obligations
Duration of expected recognition period for remaining performance obligation	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-12-26
Contract Liabilities:
Revenue, remaining peformance obligation	$ 1,374,100
Future estimated revenue to be recognised related to performance obligations
Duration of expected recognition period for remaining performance obligation	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Contract Liabilities:
Revenue, remaining peformance obligation	$ 1,202,800
Future estimated revenue to be recognised related to performance obligations
Duration of expected recognition period for remaining performance obligation	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-12-31
Contract Liabilities:
Revenue, remaining peformance obligation	$ 3,216,000
Future estimated revenue to be recognised related to performance obligations
Duration of expected recognition period for remaining performance obligation

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Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130556-203045

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- 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

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- Definition

Period in which remaining performance obligation is expected to be recognized as revenue, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130556-203045

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