Financial Instruments - Summary of Location and Fair Value (Details) - Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 30, 2017
Derivatives, Fair Value [Line Items]
Total derivative assets	$ 8	$ 1,009
Total derivative liabilities	(639)	(3,155)
Other Current Assets [Member] \| Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Other current assets: Gain positions	8	1,014
Other current assets: Loss positions	0	(5)
Other Current Liabilities [Member] \| Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Other current liability: Gain positions	148	55
Other current liability: Loss positions	$ (787)	$ (3,210)

Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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