SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Recently adopted accounting standards (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Oct. 01, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Change in accounting standard cumulative-effect adjustment	$ (1,525)	$ 0
Restatement Adjustment | Accounting Standards Update 2016-18
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease in restricted cash		8,600
Accumulated Net Investment Gain (Loss) Attributable to Parent
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Change in accounting standard cumulative-effect adjustment	$ (1,525)	$ 0