Impairment Of Long-Lived Assets And Other Lease Charges (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 28, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 28, 2020 USD ($)	Jun. 30, 2019 USD ($)
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment and other lease charges	$ 2,941	$ 367	$ 5,822	$ 1,277
Underperforming Restaurants [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment charges, number of restaurants	6	1	9	3
Initial Impairment Charge [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment and other lease charges	$ 2,600	$ 200	$ 4,100	$ 900
Previously Impairment Restaurants [Member] | Underperforming Restaurants [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment and other lease charges		100	300	200
Other Lease Charges [Member] | Underperforming Restaurants [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment and other lease charges	$ 200	$ 100	$ 1,400	$ 200