ACQUISITIONS (Bison Midstream) (Details) (USD $)	6 Months Ended			6 Months Ended	0 Months Ended		0 Months Ended			6 Months Ended
	Jun. 30, 2013	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013 SMP Holdings' equity in Bison Midstream	Jun. 04, 2013 Bison Midstream	Feb. 15, 2013 Bison Midstream	Jun. 04, 2013 Bison Midstream Limited partners, Common	Jun. 04, 2013 Bison Midstream General Partner Units	Jun. 04, 2013 Bison Midstream SMP Holdings' equity in Bison Midstream	Jun. 30, 2014 Bison Midstream Weighted Average	Jun. 30, 2014 Bison Midstream Gas Gathering Contract Minimum	Jun. 30, 2014 Bison Midstream Gas Gathering Contract Maximum
Business Acquisition [Line Items]
Useful lives										12 years	5 years	15 years
Cost of acquired entity, purchase price					$ 248,900,000
Cost of acquired entity, cash paid									200,000,000
Cost of acquired entity, equity interests issued and issuable							47,900,000	1,000,000
Purchase price assigned to Bison Gas Gathering system	303,168,000			303,168,000					303,200,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Purchase price assigned to Bison Gas Gathering system						303,168,000
Current assets						5,705,000
Property, plant, and equipment						85,477,000
Intangible assets						164,502,000
Other noncurrent assets						2,187,000
Total assets acquired						257,871,000
Current liabilities						6,112,000
Other noncurrent liabilities						2,790,000
Total liabilities assumed						8,902,000
Net identifiable assets acquired						248,969,000
Goodwill		$ 115,888,000	$ 115,888,000			$ 54,199,000