Investments - Madison (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 24, 2017	Sep. 30, 2018	Sep. 24, 2017
Ownership of Madison Paper Industries by Consolidated Subsidiary
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	50.00%		50.00%
Madison Paper Industries
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	40.00%		40.00%
Revenues	$ 0	$ 0	$ 0	$ 0
Expenses:
Cost of sales	0	(105,000)	0	(1,277,000)
General and administrative (expense)/income and other	(65,000)	60,216,000	(99,000)	59,662,000
Total (expense)/income	(65,000)	60,111,000	(99,000)	58,385,000
Operating (loss)/income	(65,000)	60,111,000	(99,000)	58,385,000
Other income/(expense)	33,000	(1,000)	81,000	(7,000)
Net (loss)/income	(32,000)	60,110,000	(18,000)	58,378,000
Distributions received	$ 0	$ 0	$ 0	$ 0