FAIR VALUE MEASUREMENTS: (Details) (Fair value measured on a recurring basis, USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 29, 2014
Estimated Fair Value
Fair value measurements
Cash and cash equivalents	$ 85,430	$ 100,108	$ 51,179
Available for sale securities	133,412	131,347	138,225
Trading securities	75,171	71,682	63,412
Total assets measured at fair value	288,976	300,461	251,591
Estimated Fair Value \| Foreign currency forward contracts
Fair value measurements
Derivative instruments, net	(3,328)	(1,939)	(1,613)
Estimated Fair Value \| Commodity futures contracts
Fair value measurements
Derivative instruments, net	(1,709)	(737)	388
Level 1
Fair value measurements
Cash and cash equivalents	85,430	100,108	51,179
Available for sale securities	2,461	2,446
Trading securities	75,171	71,682	63,412
Total assets measured at fair value	161,353	173,499	114,979
Level 1 \| Commodity futures contracts
Fair value measurements
Derivative instruments, net	(1,709)	(737)	388
Level 2
Fair value measurements
Available for sale securities	130,951	128,901	138,225
Total assets measured at fair value	127,623	126,962	136,612
Level 2 \| Foreign currency forward contracts
Fair value measurements
Derivative instruments, net	$ (3,328)	$ (1,939)	$ (1,613)

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value of the assets less the liabilities of a derivative or group of derivatives.

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Fair value of asset after deduction of liability.

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Amount of investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading.

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