Long-Term Debt and Capital Lease Obligations (Details Textual) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 27, 2018	Sep. 28, 2017	Sep. 27, 2018	Sep. 28, 2017	Mar. 01, 2018	Jan. 31, 2018	Dec. 28, 2017
Derivative, Amount of Hedged Item					$ 50,000,000
Interest Expense	$ 3,180,000	$ 3,367,000	$ 10,000,000	$ 9,454,000
Commitment Minimum Lease Payments			6,163,000
Repayments of Long-term Capital Lease Obligations			1,375,000	782,000
Obligation To Be Reduced In Next 12 Months	5,140,000		5,140,000
Interest Rate Fair Value Hedge Asset at Fair Value	$ 444,000		444,000				$ 13,000
Interest Rate Swap [Member]
Derivative, Amount of Hedged Item						$ 25,000,000
Derivative, Fixed Interest Rate						0.96%
Interest Expense			$ 13,000
Interest Rate Swap Agreements One [Member]
Derivative, Fixed Interest Rate	2.559%		2.559%
Derivative Liability, Notional Amount	$ 25,000,000		$ 25,000,000
Debt Instrument, Interest Rate, Basis for Effective Rate			one-month LIBOR 2.125%
Debt Instrument, Maturity Date			Mar. 01, 2021
Interest Rate Swap Agreements Two [Member]
Derivative, Fixed Interest Rate	2.687%		2.687%
Derivative Liability, Notional Amount	$ 25,000,000		$ 25,000,000
Debt Instrument, Interest Rate, Basis for Effective Rate			one-month LIBOR 2.125%
Debt Instrument, Maturity Date			Mar. 01, 2023
Digital Systems [Member]
Capital Leases, Balance Sheet, Assets by Major Class, Net	45,510,000		$ 45,510,000
Finite-Lived Intangible Assets, Accumulated Amortization	39,103,000		39,103,000				34,471,000
Furniture and Fixtures [Member]
Capital Leases, Balance Sheet, Assets by Major Class, Net	438,000		438,000				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	3,701,000		3,701,000				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	874,000	$ 2,424,000	2,424,000
Unsecured Senior Notes [Member]
Debt Instrument, Face Amount		$ 50,000,000		$ 50,000,000
Debt Instrument, Interest Rate, Stated Percentage		4.32%		4.32%
Mortgage Notes [Member]
Debt Instrument, Face Amount		$ 15,000,000		$ 15,000,000
Debt Instrument, Interest Rate, Basis for Effective Rate				LIBOR plus 2.75%
Repayments of Notes Payable				$ 24,226,000