Derivative Financial Instruments, Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type (Details) - Foreign Exchange Forward [Member] - USD ($) $ in Thousands	Jul. 01, 2018	Dec. 31, 2017	Jul. 02, 2017
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Net unrealized gain	$ 396	$ (2,891)	$ (2,815)
Not Designated as Hedging Instrument [Member] | Prepaid expenses and other current assets [Member]
Derivatives, Fair Value [Line Items]
Unrealized gains	1,120	0	0
Unrealized losses	(724)	0	0
Net unrealized gain	396	0	0
Not Designated as Hedging Instrument [Member] | Accrued liabilities [Member]
Derivatives, Fair Value [Line Items]
Unrealized gains	0	1,793	55
Unrealized losses	0	(4,684)	(2,870)
Net unrealized gain	0	(2,891)	(2,815)
Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Net unrealized gain	16,964	(7,934)	5,943
Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | Prepaid expenses and other current assets [Member]
Derivatives, Fair Value [Line Items]
Unrealized gains	17,388	13,666	12,220
Unrealized losses	(5,307)	(10,319)	(4,059)
Net unrealized gain	12,081	3,347	8,161
Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Unrealized gains	12,774	11,255	22,468
Unrealized losses	(2,700)	(2,376)	(5,257)
Net unrealized gain	10,074	8,879	17,211
Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | Accrued liabilities [Member]
Derivatives, Fair Value [Line Items]
Unrealized gains	911	4,215	6,403
Unrealized losses	(3,118)	(15,484)	(23,421)
Net unrealized gain	(2,207)	(11,269)	(17,018)
Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | Other liabilities [Member]
Derivatives, Fair Value [Line Items]
Unrealized gains	807	4,546	2,079
Unrealized losses	(3,791)	(13,437)	(4,490)
Net unrealized gain	$ (2,984)	$ (8,891)	$ (2,411)