FAIR VALUE MEASUREMENTS: (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair value measurements
Available for sale securities	$ 134,501	$ 131,347
Trading securities	60,584	71,682
Fair value measured on a recurring basis
Fair value measurements
Cash and cash equivalents	126,145	100,108
Available for sale securities	134,501	131,347
Trading securities	60,584	71,682
Total assets measured at fair value	318,875	300,461
Fair value measured on a recurring basis \| Foreign currency forward contracts
Fair value measurements
Derivative instruments, net	(2,626)	(1,939)
Fair value measured on a recurring basis \| Commodity futures contracts
Fair value measurements
Derivative instruments, net	271	(737)
Fair value measured on a recurring basis \| Level 1
Fair value measurements
Cash and cash equivalents	126,145	100,108
Available for sale securities	2,430	2,446
Trading securities	60,584	71,682
Total assets measured at fair value	189,430	173,499
Fair value measured on a recurring basis \| Level 1 \| Commodity futures contracts
Fair value measurements
Derivative instruments, net	271	(737)
Fair value measured on a recurring basis \| Level 2
Fair value measurements
Available for sale securities	132,071	128,901
Total assets measured at fair value	129,445	126,962
Fair value measured on a recurring basis \| Level 2 \| Foreign currency forward contracts
Fair value measurements
Derivative instruments, net	$ (2,626)	$ (1,939)

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

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Fair value of the assets less the liabilities of a derivative or group of derivatives.

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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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