Derivatives (Narrative) (Details) - USD ($)	3 Months Ended
	Apr. 01, 2017	Apr. 02, 2016
Derivative [Line Items]
Net income	$ 7,398,000	$ 2,663,000
Commodity Contract [Member]
Derivative [Line Items]
Forward purchase amount	23,700,000
Cash Flow Hedging [Member]
Derivative [Line Items]
Cash flow hedge gain (loss) to be reclassified within 12 months	2,200,000
Net income	$ 0