SCHEDULE II-VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	$ 637	$ 623	$ 666
Charged to costs and expenses	422	160	(130)
Other additions	(61)	2	201
Deductions	18	148	114
Balance at end of year	980	637	623
Balance of valuation allowance	637	623	666
Environmental Reserves [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	21,864	21,667	22,661
Charged to costs and expenses	7,491	894	76
Other additions	0	0	0
Deductions	1,351	697	1,070
Balance at end of year	28,004	21,864	21,667
Balance of valuation allowance	21,864	21,667	22,661
Valuation Allowance of Deferred Tax Assets [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	18,681	17,650	17,119
Charged to costs and expenses	7	3	(5)
Other additions	11,628	1,028	536
Deductions	0	0	0
Balance at end of year	30,316	18,681	17,650
Period increase in valuation allowance	11,600
Balance of valuation allowance	$ 18,681	$ 17,650	$ 17,119