Valuation and Qualifying Accounts (Details) - Allowance For Uncollectible Accounts [Member] - USD ($) $ in Thousands		12 Months Ended
		Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period		$ 1,455	$ 1,967	$ 1,578
Charged to Costs and Expenses		2,176	1,145	1,438
Deductions	[1]	1,685	1,657	1,049
Balance at End of Period		$ 1,946	$ 1,455	$ 1,967

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