SIGNIFICANT ACCOUNTING POLICIES (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Summary of the categories of property and equipment
Property, Plant and Equipment, net of accumulated depreciation	$ 324,669	$ 346,507
Deferred Revenue
Current - accrued compensation and other current liabilities	24,625	17,519
Long-term - other long term liabilities	$ 7,888	$ 13,000

The carrying amount of consideration received or receivable as of the balance sheet date on potential earnings that were not recognized as revenue in conformity with GAAP, and which are expected to be recognized as such within one year or the normal operating cycle, if longer, including sales, license fees, and royalties, but excluding interest income.

The noncurrent portion of deferred revenue amount as of balance sheet date. Deferred revenue is a liability related to a revenue producing activity for which revenue has not yet been recognized, and is not expected to be recognized in the next twelve months. 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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