SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Summary of Impact of Topic 606 Adoption on Unaudited Condensed Consolidated Statement of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net loss	$ (49,913)	$ 11,246	$ (53,758)	$ 10,663
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation and amortization	$ 26,634	$ 28,537	53,160	56,955
Changes in operating assets and liabilities:
Accounts receivable			(6,265)	41,527
Deferred revenue, net			3,281	$ (39,671)
Balances Without Adoption of Topic 606
Cash flows from operating activities:
Net loss			(61,385)
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation and amortization			52,545
Changes in operating assets and liabilities:
Accounts receivable			2,133
Deferred revenue, net			3,125
Accounting Standard Update 2014-09 | Effect of Change Increase / (Decrease)
Cash flows from operating activities:
Net loss			7,627
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation and amortization			615
Changes in operating assets and liabilities:
Accounts receivable			(8,398)
Deferred revenue, net			$ 156