SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Available-for-sale Investments) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 59,441	$ 31,627
Gross Unrealized Gains	96	139
Gross Unrealized Losses	(12)	0
Estimated Fair Market Value	59,525	31,766
Investments due in less than 3 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	25,392	1,500
Gross Unrealized Gains	20	1
Gross Unrealized Losses	0	0
Estimated Fair Market Value	25,412	1,501
Investments due in 4-12 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	8,959	24,127
Gross Unrealized Gains	26	83
Gross Unrealized Losses	0	0
Estimated Fair Market Value	8,985	24,210
Investments due in more than 12 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	25,090	6,000
Gross Unrealized Gains	50	55
Gross Unrealized Losses	(12)	0
Estimated Fair Market Value	25,128	6,055
Commercial paper [Member] \| Investments due in less than 3 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	9,995
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Estimated Fair Market Value	9,995
Corporate securities [Member] \| Investments due in less than 3 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	15,397	1,500
Gross Unrealized Gains	20	1
Gross Unrealized Losses	0	0
Estimated Fair Market Value	15,417	1,501
Corporate securities [Member] \| Investments due in 4-12 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	8,959	24,127
Gross Unrealized Gains	26	83
Gross Unrealized Losses	0	0
Estimated Fair Market Value	8,985	24,210
Corporate securities [Member] \| Investments due in more than 12 months [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	25,090	6,000
Gross Unrealized Gains	50	55
Gross Unrealized Losses	(12)	0
Estimated Fair Market Value	$ 25,128	$ 6,055

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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