Income Taxes Components of Deferred Tax Assets and Liabilities, Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 26, 2015
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Valuation Allowance	$ 5,400	$ 5,294
Deferred Tax Assets, Net	7,610	4,726
Federal net operating losses	5,930	4,345
State net operating losses	3,672	3,563
Federal tax credit carryforwards	3,361	2,943
State tax credit carryforwards	1,728	$ 1,731
Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 16,943
Internal Revenue Service (IRS) [Member] | Earliest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards and Tax Credit Carryforwards, Expiration Date	Dec. 31, 2029
Internal Revenue Service (IRS) [Member] | Latest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards and Tax Credit Carryforwards, Expiration Date	Dec. 31, 2036
State Taxing Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 83,088
State Taxing Authority [Member] | Earliest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards and Tax Credit Carryforwards, Expiration Date	Dec. 31, 2017
State Taxing Authority [Member] | Latest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards and Tax Credit Carryforwards, Expiration Date	Dec. 31, 2037