REVENUE - Schedule of Disaggregated Revenue by Geographic Area and Major Products and Services Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation Of Revenue [Line Items]
Total revenues	$ 100,187	$ 127,479	$ 331,281	$ 372,982
All Other Segments
Disaggregation Of Revenue [Line Items]
Total revenues	534	19,860	26,978	50,281
Reportable Segments
Disaggregation Of Revenue [Line Items]
Total revenues	99,653	107,619	304,303	322,701
Reportable Segments | Utica Shale
Disaggregation Of Revenue [Line Items]
Total revenues	8,865	7,974	23,951	28,437
Reportable Segments | Williston Basin
Disaggregation Of Revenue [Line Items]
Total revenues	21,118	29,010	77,440	90,850
Reportable Segments | DJ Basin
Disaggregation Of Revenue [Line Items]
Total revenues	7,867	3,782	17,839	10,355
Reportable Segments | Permian Basin
Disaggregation Of Revenue [Line Items]
Total revenues	4,885		12,545
Reportable Segments | Piceance Basin
Disaggregation Of Revenue [Line Items]
Total revenues	33,111	38,683	101,995	116,689
Reportable Segments | Barnett Shale
Disaggregation Of Revenue [Line Items]
Total revenues	17,820	21,020	52,452	53,345
Reportable Segments | Marcellus Shale
Disaggregation Of Revenue [Line Items]
Total revenues	5,987	7,150	18,081	23,025
Gathering Services and Related Fees
Disaggregation Of Revenue [Line Items]
Total revenues	80,968	86,427	243,039	260,373
Gathering Services and Related Fees | All Other Segments
Disaggregation Of Revenue [Line Items]
Total revenues	0	(1,778)	(2,045)	(4,123)
Gathering Services and Related Fees | Reportable Segments
Disaggregation Of Revenue [Line Items]
Total revenues	80,968	88,205	245,084	264,496
Gathering Services and Related Fees | Reportable Segments | Utica Shale
Disaggregation Of Revenue [Line Items]
Total revenues	8,865	7,974	23,951	28,437
Gathering Services and Related Fees | Reportable Segments | Williston Basin
Disaggregation Of Revenue [Line Items]
Total revenues	16,685	18,020	58,076	58,792
Gathering Services and Related Fees | Reportable Segments | DJ Basin
Disaggregation Of Revenue [Line Items]
Total revenues	7,039	2,708	14,784	7,395
Gathering Services and Related Fees | Reportable Segments | Permian Basin
Disaggregation Of Revenue [Line Items]
Total revenues	986		1,938
Gathering Services and Related Fees | Reportable Segments | Piceance Basin
Disaggregation Of Revenue [Line Items]
Total revenues	30,120	34,035	92,515	100,812
Gathering Services and Related Fees | Reportable Segments | Barnett Shale
Disaggregation Of Revenue [Line Items]
Total revenues	11,286	18,318	35,739	46,035
Gathering Services and Related Fees | Reportable Segments | Marcellus Shale
Disaggregation Of Revenue [Line Items]
Total revenues	5,987	7,150	18,081	23,025
Natural Gas, NGLs and Condensate Sales
Disaggregation Of Revenue [Line Items]
Total revenues	12,219	34,017	68,438	92,025
Natural Gas, NGLs and Condensate Sales | All Other Segments
Disaggregation Of Revenue [Line Items]
Total revenues	(110)	21,625	28,660	54,511
Natural Gas, NGLs and Condensate Sales | Reportable Segments
Disaggregation Of Revenue [Line Items]
Total revenues	12,329	12,392	39,778	37,514
Natural Gas, NGLs and Condensate Sales | Reportable Segments | Utica Shale
Disaggregation Of Revenue [Line Items]
Total revenues	0	0	0	0
Natural Gas, NGLs and Condensate Sales | Reportable Segments | Williston Basin
Disaggregation Of Revenue [Line Items]
Total revenues	1,878	7,953	11,231	23,149
Natural Gas, NGLs and Condensate Sales | Reportable Segments | DJ Basin
Disaggregation Of Revenue [Line Items]
Total revenues	93	112	279	271
Natural Gas, NGLs and Condensate Sales | Reportable Segments | Permian Basin
Disaggregation Of Revenue [Line Items]
Total revenues	3,797		10,424
Natural Gas, NGLs and Condensate Sales | Reportable Segments | Piceance Basin
Disaggregation Of Revenue [Line Items]
Total revenues	1,733	3,538	6,139	12,379
Natural Gas, NGLs and Condensate Sales | Reportable Segments | Barnett Shale
Disaggregation Of Revenue [Line Items]
Total revenues	4,828	789	11,705	1,715
Natural Gas, NGLs and Condensate Sales | Reportable Segments | Marcellus Shale
Disaggregation Of Revenue [Line Items]
Total revenues	0	0	0	0
Other Revenues
Disaggregation Of Revenue [Line Items]
Total revenues	7,000	7,035	19,804	20,584
Other Revenues | All Other Segments
Disaggregation Of Revenue [Line Items]
Total revenues	644	13	363	(107)
Other Revenues | Reportable Segments
Disaggregation Of Revenue [Line Items]
Total revenues	6,356	7,022	19,441	20,691
Other Revenues | Reportable Segments | Utica Shale
Disaggregation Of Revenue [Line Items]
Total revenues	0	0	0	0
Other Revenues | Reportable Segments | Williston Basin
Disaggregation Of Revenue [Line Items]
Total revenues	2,555	3,037	8,133	8,909
Other Revenues | Reportable Segments | DJ Basin
Disaggregation Of Revenue [Line Items]
Total revenues	735	962	2,776	2,689
Other Revenues | Reportable Segments | Permian Basin
Disaggregation Of Revenue [Line Items]
Total revenues	102		183
Other Revenues | Reportable Segments | Piceance Basin
Disaggregation Of Revenue [Line Items]
Total revenues	1,258	1,110	3,341	3,498
Other Revenues | Reportable Segments | Barnett Shale
Disaggregation Of Revenue [Line Items]
Total revenues	1,706	1,913	5,008	5,595
Other Revenues | Reportable Segments | Marcellus Shale
Disaggregation Of Revenue [Line Items]
Total revenues	$ 0	$ 0	$ 0	$ 0