Long-Term Debt and Capital Lease Obligations (Details Textual) - USD ($)	3 Months Ended	6 Months Ended
	Jun. 28, 2018	Jun. 28, 2018	Jun. 29, 2017	Mar. 01, 2018	Jan. 31, 2018	Dec. 28, 2017
Derivative, Amount of Hedged Item				$ 50,000,000	$ 25,000,000
Derivative Liability, Notional Amount	$ 25,000,000	$ 25,000,000
Term Of Licensing Agreement		10 years
Commitment Minimum Lease Payments		$ 6,163,000
Repayments of Long-term Capital Lease Obligations		901,000	$ 516,000
Obligation To Be Reduced In Next 12 Months	5,312,000	5,312,000
Interest Rate Fair Value Hedge Asset at Fair Value	119,000	119,000				$ 13,000
Digital Systems [Member]
Capital Leases, Balance Sheet, Assets by Major Class, Net	45,510,000	45,510,000				45,510,000
Finite-Lived Intangible Assets, Accumulated Amortization	37,559,000	37,559,000				34,471,000
Furniture and Fixtures [Member]
Capital Leases, Balance Sheet, Assets by Major Class, Net	377,000	377,000				255,000
Capital Leased Assets, Gross	1,712,000	1,712,000				1,712,000
Building and Building Improvements [Member]
Capital Leases, Balance Sheet, Assets by Major Class, Net	3,204,000	3,204,000				2,300,000
Capital Leased Assets, Gross	25,648,000	25,648,000				$ 25,648,000
Furniture and Fixtures AND Building and Building Improvements [Member]
Repayments of Long-term Capital Lease Obligations	$ 808,000	$ 1,616,000
Unsecured Senior Notes [Member]
Debt Instrument, Face Amount			$ 50,000,000
Debt Instrument, Interest Rate, Stated Percentage			4.32%
Interest Rate Swap [Member]
Derivative, Fixed Interest Rate				2.559%	0.96%
Derivative, Variable Interest Rate	2.00%	2.00%
Decrease In Interest Expense		$ 13,000
Derivative, Description of Variable Rate Basis		one-month LIBOR 2.000%
Mortgage Notes [Member]
Debt Instrument, Face Amount			$ 15,000,000
Debt Instrument, Interest Rate, Basis for Effective Rate			LIBOR plus 2.75%
Debt Instrument, Interest Rate, Effective Percentage			3.81%
Repayments of Notes Payable			$ 24,226,000
First Interest Rate Swap [Member]
Derivative, Fixed Interest Rate	2.687%	2.687%
Derivative Liability, Notional Amount				$ 25,000,000
Derivative, Description of Variable Rate Basis		one-month LIBOR 2.000%
Derivative, Basis Spread on Variable Rate	2.00%	2.00%