ACQUISITIONS (Pro Forma) (Details) (USD $)	3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended		3 Months Ended	6 Months Ended			18 Months Ended	3 Months Ended	6 Months Ended		3 Months Ended	6 Months Ended		3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	1 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2013 Limited partners, Common	Jun. 30, 2014 Limited partners, Common	Jun. 30, 2013 Limited partners, Common	Jun. 30, 2013 Subordinated units	Jun. 30, 2014 Subordinated units	Jun. 30, 2013 Subordinated units	Jun. 30, 2013 Bison Midstream	Jun. 30, 2014 Red Rock Gathering Company, LLC	Jun. 30, 2013 Red Rock Gathering Company, LLC	Jun. 30, 2014 Red Rock Gathering Company, LLC	Jun. 30, 2013 Red Rock Gathering Company, LLC	Jun. 30, 2013 Red Rock Gathering Company, LLC	Jun. 30, 2014 Red Rock Gathering Company, LLC	Jun. 30, 2013 Red Rock Gathering Company, LLC	Jun. 30, 2013 Bison Midstream and Mountaineer Midstream	Jun. 30, 2013 Bison Midstream and Mountaineer Midstream	Jun. 30, 2013 Acquisition-related Costs Bison Midstream and Mountaineer Midstream	Jun. 30, 2013 Acquisition-related Costs Bison Midstream and Mountaineer Midstream	Mar. 31, 2014 General partner	Jun. 30, 2014 General partner	Jun. 30, 2013 General partner
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Nonrecurring transaction cost																					$ 2,400,000	$ 2,400,000
Incremental borrowings on revolving credit facility											310,000,000	100,000,000
Common unit issuance												5,300,000
General partner interest (as a percent)																							2.00%	2.00%
Revenues	80,796,000	71,461,000	156,998,000	133,446,000									12,176,000	11,313,000	23,035,000	12,176,000	34,589,000	23,034,000	15,951,000	23,482,000
Net income	4,036,000	8,767,000	10,409,000	22,630,000									1,234,000	2,828,000	2,030,000	1,234,000	10,181,000	2,031,000	54,000	641,000				1,232,000	411,000
Pro forma total revenues		74,480,000	156,998,000	145,596,000
Pro forma net income		$ 9,805,000	$ 9,905,000	$ 18,110,000
Pro forma EPU, basic and diluted					$ 0.16	$ 0.16	$ 0.30	$ 0.16	$ 0.12	$ 0.30