Valuation and Qualifying Accounts (Details) - Allowance For Uncollectible Accounts [Member] - USD ($) $ in Thousands		12 Months Ended
		Dec. 26, 2020	Dec. 28, 2019	Dec. 29, 2018
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period		$ 2,757	$ 2,090	$ 1,946
Charged to Costs and Expenses		1,556	1,975	1,144
Charged to Accounts
Deductions	[1]	1,886	1,308	1,000
Balance at End of Period		$ 2,427	$ 2,757	$ 2,090

[1] Deductions are uncollectible accounts written off, net of recoveries.