SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease in retained earnings	$ (909,472)		$ (916,971)
Cumulative effect adjustments			(88,594)
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustments			(78,042)
Accumulated Other Comprehensive Income (Loss)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustments			$ (10,552)
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use asset and lease liability	$ 21,000
ASU No. 2016-01 - Financial Instruments - Recognition and Measurement of Financial Assets and Financial Liabilities | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustments		$ 10,600
ASU No. 2016-01 - Financial Instruments - Recognition and Measurement of Financial Assets and Financial Liabilities | Accumulated Other Comprehensive Income (Loss)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustments		(10,600)
Difference between Revenue Guidance in Effect before and after Topic 606 | ASU No. 2014-09 - Revenue from Contracts with Customers
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease in retained earnings		$ 88,600