Impairment Of Long-Lived Assets And Other Lease Charges (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 03, 2021 USD ($) restaurant	Sep. 27, 2020 USD ($)	Jun. 28, 2020 USD ($)	Mar. 29, 2020 USD ($)	Dec. 29, 2019 USD ($)	Sep. 29, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Jan. 03, 2021 USD ($)	Dec. 29, 2019 USD ($)	Dec. 30, 2018 USD ($)
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment and other lease charges	$ 5,000	$ 2,000	$ 2,900	$ 2,900	$ 1,800	$ 500	$ 400	$ 900	$ 12,778	$ 3,564	$ 3,685
Impairment charges									8,200	1,700	2,700
Sale Leaseback Transaction Current Period Loss Recognized											$ 800
Sale Leaseback Losses, number of restaurants											4
Other lease charges									$ 4,600	$ 1,900	$ 200
Asset impairment charges, number of restaurants									15	7	6
Write Off Of Defective Product											$ 1,900
Previously Impaired [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment charges									$ 1,200	$ 300	400
Initial Impairments [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment charges									5,000	$ 1,300	$ 400
First Right Of Refusal
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment charges									$ 2,000
Other Lease Charges
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment charges, number of restaurants | restaurant	22