SEGMENT INFORMATION - Reconciliation of Net Income to Adjusted EBITDA (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting [Abstract]
(Loss) income before income taxes and income (loss) from equity method investees	$ (5,402,000)	$ 525,000
Add:
Corporate and Other	10,623,000	10,093,000
Interest expense	15,122,000	16,716,000
Early extinguishment of debt	0	22,020,000
Deferred Purchase Price Obligation	21,658,000	20,883,000
Depreciation and amortization	26,526,000	28,418,000
Proportional adjusted EBITDA for equity method investees	10,477,000	9,073,000
Adjustments related to MVC shortfall payments	0	(28,640,000)
Adjustments related to capital reimbursement activity	40,000	0
Unit-based and noncash compensation	1,962,000	2,128,000
(Gain) loss on asset sales, net	(74,000)	3,000
Long-lived asset impairment	0	284,000
Total of reportable segments' measures of profit or loss	$ 80,932,000	$ 81,503,000