SEGMENT INFORMATION - Reconciliation of Net Income (Loss) to Adjusted EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting [Abstract]
Income (loss) before income taxes and equity method investment income (loss)	$ 25,132	$ (10,431)	$ 78,862	$ (45,757)
Add:
Corporate and Other expense	6,874	7,119	28,484	32,024
Interest expense	19,018	23,462	64,836	68,547
Gain on early extinguishment of debt	(24,690)		(78,925)	0
Depreciation and amortization	29,739	27,677	89,505	83,030
Proportional adjusted EBITDA for equity method investees	7,129	10,435	22,582	29,584
Adjustments related to MVC shortfall payments	2,292	3,534	(859)	2,868
Adjustments related to capital reimbursement activity	(328)	(145)	(776)	(1,906)
Unit-based and noncash compensation	1,622	1,291	6,191	5,370
Gain on asset sales, net	(104)	(347)	(270)	(1,595)
Long-lived asset impairment			4,475	45,021
Goodwill impairment		16,211	0	16,211
Total of reportable segments' measures of profit	$ 66,684	$ 78,806	$ 214,105	$ 233,397