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Restructuring Charges and Asset Impairments (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended			12 Months Ended
	Jan. 01, 2021	Jun. 26, 2020	Dec. 27, 2019	Jan. 01, 2021	Dec. 27, 2019	Dec. 28, 2018
Restructuring Cost And Reserve [Line Items]
Restructuring charges and asset impairments				$ 10,488	$ 4,514	$ 6,269
Restructuring costs	$ 1,600	$ 5,000	$ 3,300	6,603	3,334
Restructuring Reserve	2,292		1,584	2,292	1,584
Impairment of assets	$ 3,900		$ 1,200	3,885	1,180	$ 6,269
Hackett Institute Enterprise Analytics Program [Member]
Restructuring Cost And Reserve [Line Items]
Impairment of assets					$ 1,200
Real Estate Leases [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges and asset impairments				4,800
Impairment Related Costs [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges and asset impairments				4,800
COVID-19 [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges and asset impairments				$ 5,700