Investments - Madison (Details) - Madison Paper Industries - USD ($)	3 Months Ended		6 Months Ended
	Jul. 01, 2018	Jun. 25, 2017	Jul. 01, 2018	Jun. 25, 2017
Schedule of Equity Method Investments [Line Items]
Revenues	$ 0	$ 0	$ 0	$ 0
Expenses:
Cost of sales	0	(118,000)	0	(1,172,000)
General and administrative income/(expense) and other	(43,000)	(528,000)	(34,000)	(554,000)
Total expense	(43,000)	(646,000)	(34,000)	(1,726,000)
Operating loss	(43,000)	(646,000)	(34,000)	(1,726,000)
Other income/(expense)	28,000	(4,000)	48,000	(6,000)
Net (loss)/income	(15,000)	(650,000)	14,000	(1,732,000)
Distributions received	$ 0	$ 0	$ 0	$ 0