MARKETABLE SECURITIES AND FAIR VALUE MEASUREMENTS - Summary of fair value of available-for-sale securities (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 114,381	$ 95,878
Gross Unrealized Gains	138	38
Gross Unrealized Losses	(36)	(44)
Fair Value	114,483	95,872
Current
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		57,087
Gross Unrealized Gains		23
Gross Unrealized Losses		(37)
Fair Value		57,073
Non Current
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		38,791
Gross Unrealized Gains		15
Gross Unrealized Losses		(7)
Fair Value		38,799
U.S. Federal Treasury and U.S. government agencies securities-short term & long term \| Current
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		17,259
Gross Unrealized Gains		1
Gross Unrealized Losses		(1)
Fair Value		17,259
U.S. Federal Treasury and U.S. government agencies securities-short term & long term \| Non Current
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		33,556
Gross Unrealized Gains		13
Gross Unrealized Losses		(6)
Fair Value		33,563
Corporate debt securities-short term & long term \| Current
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	64,921	39,828
Gross Unrealized Gains	45	22
Gross Unrealized Losses	(22)	(36)
Fair Value	64,944	39,814
Corporate debt securities-short term & long term \| Non Current
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	49,460	5,235
Gross Unrealized Gains	93	2
Gross Unrealized Losses	(14)	(1)
Fair Value	$ 49,539	$ 5,236

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

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