FAIR VALUE MEASUREMENTS (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Included in cash and cash equivalents
Cost	$ 18,796	$ 12,885
Gross Unrealized Losses	(1)
Estimated Fair Value	18,795	12,885
Restricted cash
Cost	794	793
Estimated Fair Value	794	793
Marketable securities
Cost	73,431	137,263
Gross Unrealized Gains	48	133
Gross Unrealized Losses	(7)	(55)
Estimated Fair Value	73,472	137,341
Money market funds
Included in cash and cash equivalents
Cost	15,660	12,885
Estimated Fair Value	15,660	12,885
Certificates of deposit
Restricted cash
Cost	794	793
Estimated Fair Value	794	793
Certificates of deposit \| Investments due in less than 1 year
Marketable securities
Cost		329
Estimated Fair Value		329
Corporate notes
Included in cash and cash equivalents
Cost	3,136
Gross Unrealized Losses	(1)
Estimated Fair Value	3,135
Corporate notes \| Investments due in less than 1 year
Marketable securities
Cost	44,190	50,556
Gross Unrealized Gains	22	19
Gross Unrealized Losses	(7)	(28)
Estimated Fair Value	44,205	50,547
Corporate notes \| Investments due in 1 to 2 years
Marketable securities
Cost		25,113
Gross Unrealized Gains		30
Gross Unrealized Losses		(14)
Estimated Fair Value		25,129
Government-sponsored enterprise securities \| Investments due in less than 1 year
Marketable securities
Cost	8,618	15,061
Gross Unrealized Gains	5	25
Gross Unrealized Losses		(1)
Estimated Fair Value	8,623	15,085
Government-sponsored enterprise securities \| Investments due in 1 to 2 years
Marketable securities
Cost		6,998
Gross Unrealized Gains		18
Gross Unrealized Losses		(12)
Estimated Fair Value		7,004
Commercial paper \| Investments due in less than 1 year
Marketable securities
Cost	20,623	39,206
Gross Unrealized Gains	21	41
Estimated Fair Value	$ 20,644	$ 39,247

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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 includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Company may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months.

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The carrying amounts of cash and cash equivalent items which are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against short-term borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. For a classified balance sheet represents the current portion only (the noncurrent portion has a separate concept); there is a separate and distinct element for unclassified presentations.

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