General (Details Textual) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 29, 2016	Sep. 24, 2015	Sep. 29, 2016	Sep. 24, 2015	Dec. 31, 2015
Summary of Significant Accounting Policies [Line Items]
Depreciation	$ 10,537,000	$ 10,353,000	$ 31,214,000	$ 29,955,000
Percentage Of Cash Dividends			110.00%
Available-for-sale Securities, Fair Value Disclosure	70,000		$ 70,000		$ 70,000
Interest Rate Fair Value Hedge Liability at Fair Value	88,000		88,000
Interest Rate Fair Value Hedge Asset at Fair Value					16,000
Impairment of Long-Lived Assets to be Disposed of				319,000
Trading Securities	$ 1,659,000		$ 1,659,000
Impairment of Long-Lived Assets Held-for-use				2,600,000
Accounting Standards Update 2015-03 [Member]
Summary of Significant Accounting Policies [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets					$ 404,000
Accounting Standards Update 2015-03 [Member] | Interest Expense [Member]
Summary of Significant Accounting Policies [Line Items]
Amortization of Debt Issuance Costs		$ 110,000		$ 329,000