FAIR VALUE MEASUREMENTS: (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Fair value measurements
Available for sale securities	$ 131,347us-gaap_AvailableForSaleSecurities	$ 118,647us-gaap_AvailableForSaleSecurities
Trading securities	71,682us-gaap_TradingSecurities	63,215us-gaap_TradingSecurities
Fair value measured on a recurring basis \| Estimated Fair Value
Fair value measurements
Cash and cash equivalents	100,108	88,283
Available for sale securities	131,347	118,647
Trading securities	71,682	63,215
Total assets measured at fair value	300,461	269,331
Fair value measured on a recurring basis \| Estimated Fair Value \| Foreign currency forward contracts
Fair value measurements
Derivative instruments, net	(1,939)	(684)
Fair value measured on a recurring basis \| Estimated Fair Value \| Commodity futures contracts
Fair value measurements
Derivative instruments, net	(737)	(130)
Fair value measured on a recurring basis \| Level 1
Fair value measurements
Cash and cash equivalents	100,108	88,283
Available for sale securities	2,446
Trading securities	71,682	63,215
Total assets measured at fair value	173,499	151,368
Fair value measured on a recurring basis \| Level 2
Fair value measurements
Available for sale securities	128,901	118,647
Total assets measured at fair value	$ 126,962	$ 117,963

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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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.

+ References

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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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