FAIR VALUE MEASUREMENTS (Details 2) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Marketable securities with unrealized losses
Less Than 12 Months - Estimated Fair Value	$ 92,300	$ 111,321
Less Than 12 Months - Gross Unrealized Losses	(62)	(100)
Total - Estimated Fair Value	92,300	111,321
Total - Gross Unrealized Losses	(62)	(100)
Government-sponsored enterprise securities (due in less than 1 year)
Marketable securities with unrealized losses
Less Than 12 Months - Estimated Fair Value	400	400
Less Than 12 Months - Gross Unrealized Losses	(1)	(1)
Total - Estimated Fair Value	400	400
Total - Gross Unrealized Losses	(1)	(1)
Government-sponsored enterprise securities (due in 1 to 2 years)
Marketable securities with unrealized losses
Less Than 12 Months - Estimated Fair Value	5,805	5,549
Less Than 12 Months - Gross Unrealized Losses	(1)	(7)
Total - Estimated Fair Value	5,805	5,549
Total - Gross Unrealized Losses	(1)	(7)
Corporate notes (due in less than 1 year)
Marketable securities with unrealized losses
Less Than 12 Months - Estimated Fair Value	80,083	92,989
Less Than 12 Months - Gross Unrealized Losses	(56)	(63)
Total - Estimated Fair Value	80,083	92,989
Total - Gross Unrealized Losses	(56)	(63)
Corporate notes (due in 1 to 2 years)
Marketable securities with unrealized losses
Less Than 12 Months - Estimated Fair Value	6,012	12,383
Less Than 12 Months - Gross Unrealized Losses	(4)	(29)
Total - Estimated Fair Value	6,012	12,383
Total - Gross Unrealized Losses	$ (4)	$ (29)

Amount of gross unrealized loss on securities classified as available-for-sale securities that have been in a loss position as of the reporting date.

No definition available.

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- Definition

Amount of gross unrealized loss on securities classified as available-for-sale securities that have been in a loss position for less than twelve months as of the reporting date.

+ References

No definition available.

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- Definition

This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

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- Definition

This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

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-Section 50

-Paragraph 6

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

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