Cash and cash equivalents accumulated gross unrealized gain before tax.

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Cash and cash equivalents accumulated gross unrealized loss before tax.

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Cash, cash equivalents and short term investments fair value disclosure.

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- Definition

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Cash 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 customer may deposit additional funds at any time and 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. Short-term investments, exclusive of cash equivalents, generally consist of marketable securities intended to be sold within one year (or the normal operating cycle if longer) and may include trading securities, available-for-sale securities, or held-to-maturity securities (if maturing within one year), as applicable.

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Schedule of Cash, Cash Equivalents and Short Term Investments) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Cash And Cash Equivalents [Line Items]
Cost	$ 38,158	$ 24,654	$ 47,648	$ 9,623
Cost	92,922	72,451
Gross Unrealized Gains	198	163
Gross Unrealized Losses	(568)	(392)
Estimated fair value	92,552	72,222
Cash [Member]
Cash And Cash Equivalents [Line Items]
Cost	23,948	24,454
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated fair value	23,948	24,454
Money market funds [Member]
Cash And Cash Equivalents [Line Items]
Cost	5,227	200
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated fair value	5,227	200
Treasury bills [Member]
Cash And Cash Equivalents [Line Items]
Cost	8,983
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Estimated fair value	8,983
Government and agency securities [Member]
Cash And Cash Equivalents [Line Items]
Cost	47,697	42,220
Gross Unrealized Gains	175	135
Gross Unrealized Losses	(515)	(355)
Estimated fair value	47,357	42,000
Corporate debt securities [Member]
Cash And Cash Equivalents [Line Items]
Cost	7,067	5,577
Gross Unrealized Gains	23	28
Gross Unrealized Losses	(53)	(37)
Estimated fair value	$ 7,037	$ 5,568