Amount of deferred revenue as of balance sheet date. Deferred revenue represents collections of cash or other assets related to a revenue producing activity for which revenue has not yet been recognized. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

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Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

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REVENUE RECOGNITION AND CONTRACTS WITH CUSTOMERS (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred Revenue		$ 0
Retained Earnings (Accumulated Deficit)	$ (332,058)	(306,813)	$ (309,287)
Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue, Remaining Performance Obligation	$ 2,740
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred Revenue			2,474
Retained Earnings (Accumulated Deficit)			$ (309,287)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] \| Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Retained Earnings (Accumulated Deficit)		2,474
Transferred over Time [Member] \| Difference between Revenue Guidance in Effect before and after Topic 606 [Member] \| Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred Revenue		$ (2,474)