Contract Liabilities - Performance Obligations (Details)	Sep. 28, 2019 USD ($)
Contract Liabilities:
Revenue, remaining peformance obligation	$ 9,762,800
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-09-29
Contract Liabilities:
Revenue, remaining peformance obligation	$ 433,200
Future estimated revenue to be recognised related to performance obligations
Duration of expected recognition period for remaining performance obligation	3 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-12-29
Contract Liabilities:
Revenue, remaining peformance obligation	$ 1,693,100
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]: 2020-12-27
Contract Liabilities:
Revenue, remaining peformance obligation	$ 1,554,300
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	$ 1,409,400
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	$ 1,238,100
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]: 2023-12-31
Contract Liabilities:
Revenue, remaining peformance obligation	$ 3,434,700
Future estimated revenue to be recognised related to performance obligations
Duration of expected recognition period for remaining performance obligation