Quarterly Financial Information (Narrative) (Details) $ in Thousands	3 Months Ended		4 Months Ended		12 Months Ended
	Sep. 06, 2016 USD ($)	Sep. 08, 2015 USD ($) store	Dec. 27, 2016 USD ($) store	Dec. 29, 2015 USD ($) store	Dec. 27, 2016 USD ($) store	Dec. 29, 2015 USD ($) store	Dec. 30, 2014 USD ($)
Quarterly Financial Information [Line items]
Impairment charges		$ 3,200	$ 600		$ 598	$ 3,248	$ 3,536
Lease termination and closing costs			900	$ 1,400	1,031	1,386
Severance Costs			$ 800
General And Administrative Expense					$ 25,924	$ 23,111	$ 20,537
Easement claim expense [Member]
Quarterly Financial Information [Line items]
General And Administrative Expense	$ 400
Locations with impairment charges [Member]
Quarterly Financial Information [Line items]
Number of restaurants owned and operated | store		1	2		2
Locations with lease termination costs [Member]
Quarterly Financial Information [Line items]
Number of restaurants owned and operated | store			1	2	1	2