Impairment Of Long-Lived Assets And Other Lease Charges (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($)	Oct. 01, 2017 USD ($)	Sep. 30, 2018 USD ($)	Oct. 01, 2017 USD ($)
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment and other lease charges	$ 164	$ 1,039	$ 3,354	$ 2,002
Write-off of Equipment [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment and other lease charges			1,873
Sale-leaseback [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment and other lease charges	71		716
Underperforming Restaurants [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment and other lease charges	$ 85		$ 620	$ 461
Asset impairment charges, number of restaurants				4
Previously Impaired [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment and other lease charges		185		$ 543
Changes in Future Costs [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment and other lease charges		$ 589
Closed Restaurants [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment and other lease charges				$ 943
Asset impairment charges, number of restaurants				4