SCHEDULE II-VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 26, 2015	Dec. 27, 2014
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year		$ 623	$ 666	$ 2,391
Charged to costs and expenses		160	(130)	(500)
Other additions	[1]	2	201	18
Deductions		148	114	1,243
Balance at end of year		637	623	666
Environmental Reserves [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year		21,667	22,661	23,637
Charged to costs and expenses		894	76	1,187
Other additions		0	0	0
Deductions		697	1,070	2,163
Balance at end of year		21,864	21,667	22,661
Valuation Allowance for Deferred Tax Assets [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year		17,650	17,119	22,544
Charged to costs and expenses		3	(5)	(5,630)
Other additions		1,028	536	2,282
Deductions		0	0	2,077
Balance at end of year		$ 18,681	$ 17,650	$ 17,119

[1] Other consists primarily of bad debt recoveries as well as the effect of fluctuating foreign currency exchange rates in all years presented.