Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Jun. 24, 2018	Dec. 31, 2017	Jun. 25, 2017	Jun. 26, 2016
Components Of Deferred Tax Assets And Liabilities [Abstract]
Investments, including unconsolidated affiliates	$ 5,429		$ 7,737
State tax credits	411		338
Accrued liabilities and valuation reserves	2,829		3,952
NOL carryforwards	10,008		7,854
Intangible assets, net	2,089		3,932
Incentive compensation plans	2,130		2,487
Provisional charge, net of foreign tax credits	5,430	$ 3,901	789
Capital loss carryforward	1,105		1,746
Research credit carryforward			1,115
Other items	2,226		5,224
Total gross deferred tax assets	31,657		35,174
Valuation allowance	(15,143)		(17,957)	$ (13,550)
Net deferred tax assets	16,514		17,217
PP&E	(20,153)		(26,417)
Other	(736)		(63)
Total deferred tax liabilities	(20,889)		(26,480)
Net deferred tax liabilities	$ (4,375)		$ (9,263)