SUPPLEMENTAL INFORMATION - NATURAL GAS AND CRUDE OIL PROPERTIES Schedule of Developed and Undeveloped Reserves (Unaudited) (Details)	12 Months Ended
	Dec. 31, 2014 bbl	Dec. 31, 2013 bbl		Dec. 31, 2012 bbl		Dec. 31, 2019 Rate	Dec. 31, 2018 Rate	Dec. 31, 2017 Rate	Dec. 31, 2016 Rate	Dec. 31, 2015 Rate	Dec. 31, 2011 bbl
Schedule of Developed and Undeveloped Reserves [Line Items]
Proved Developed and Undeveloped Reserves, Net	250,129,000	265,774,000		192,810,000							169,248,000
Undeveloped Reserves Converted to Developed	0	0		0
Revisions of Previous Estimates	(64,825,000)	(46,480,000)		(58,639,000)
Extensions, Discoveries, and Other Additions	98,029,000	141,935,000		67,941,000
Purchases of Reserves	17,000	1,043,000		33,420,000
Dispositions	(39,572,000)	(16,104,000)		(10,891,000)
Production	(9,294,000)	(7,430,000)		(8,269,000)
Crude Oil Equivalent (Boe)
Schedule of Developed and Undeveloped Reserves [Line Items]
Proved Developed and Undeveloped Reserves, Net	250,129,000	265,774,000	[1]	192,810,000	[2]						169,248,000	[3]
Revisions of Previous Estimates	(64,825,000)	(46,480,000)		(58,639,000)
Extensions, Discoveries, and Other Additions	98,029,000	141,935,000		67,941,000
Purchases of Reserves	17,000	1,043,000		33,420,000
Dispositions	(39,572,000)	(16,104,000)		(10,891,000)
Production	(9,294,000)	(7,430,000)		(8,269,000)
Year-over-Year Activity [Domain]
Schedule of Developed and Undeveloped Reserves [Line Items]
Revisions of Previous Estimates	(65,000,000)	46,000,000		59,000,000
Extensions, Discoveries, and Other Additions	98,000,000	142,000,000		68,000,000
Purchases of Reserves		1,000,000		33,000,000
Dispositions	(40,000,000)	(16,000,000)		(11,000,000)
Increase (decrease) in proved reserves	(16,000,000)
Majority of downward revision of our previous estimate of proved reserves	(69,000,000)	(55,000,000)
Change in drilling plans	(55,000,000)
Downward revisions due to adjustments in previous PUD well spacing plans	(2,000,000)	(32,000,000)
Downward revisions in reserves due to abandoned leases	(1,000,000)	(9,000,000)
Downward revisions in reserves due to our shift from vertical to horizontal drilling		(11,000,000)
Downward revisions Wattenberg Field related to PUDs that are no longer in our core drilling area	(8,000,000)	(3,000,000)
Downward revision in reserves due to increase in operating costs	(3,000,000)			(1,000,000)
Revisions due to asset performance	(2,000,000)	2,000,000		2,000,000
Revision in reserves due to production from uneconomic or divested wells	2,000,000	2,000,000
Revisions due to change in commodity pricing	1,000,000	1,000,000		(40,000,000)
Asset performance Wattenberg field	1,000,000
Reserve discoveries from non-PUD drilling	16,000,000	17,000,000
Extension and discoveries from new proved undeveloped reserves	96,000,000	125,000,000
Extension and discoveries due to adjustments in wells spacing in Wattenberg Field and Marcellus Shale	78,000,000	32,000,000
Extension and discoveries in the Marcellus Shale		18,000,000
Extension and discoveries in the Utica Shale	2,000,000	14,000,000
Reserve discoveries, refracs not added in prior year report	2,000,000
Adjustments for geological reasons				(8,000,000)
Revision due to SEC 5 Year Rule				(13,000,000)
Revisions due to interest adjustments		3,000,000		500,000
Reserve discoveries, Eastern Operating Region				10,000,000
Reserve discoveries, Wattenberg Field	96,000,000	110,000,000		59,000,000
Development Wells Drilled, Net Productive				0
PUD conversion rate	7.00%					16.00%	19.00%	22.00%	27.00%	16.00%
Developed [Member]
Schedule of Developed and Undeveloped Reserves [Line Items]
Proved Developed and Undeveloped Reserves, Net	74,905,000	75,553,000		81,753,000							78,558,000
Undeveloped Reserves Converted to Developed	12,730,000	3,212,000		7,655,000
Revisions of Previous Estimates	(22,827,000)	(6,751,000)		(18,318,000)
Extensions, Discoveries, and Other Additions	27,957,000	19,830,000		11,298,000
Purchases of Reserves	17,000	1,043,000		13,542,000
Dispositions	(9,231,000)	(16,104,000)		(2,713,000)
Production	(9,294,000)	(7,430,000)		(8,269,000)
Undeveloped [Member]
Schedule of Developed and Undeveloped Reserves [Line Items]
Proved Developed and Undeveloped Reserves, Net	175,224,000	190,221,000		111,057,000							90,690,000
Undeveloped Reserves Converted to Developed	(12,730,000)	(3,212,000)		(7,655,000)
Revisions of Previous Estimates	(41,998,000)	(39,729,000)		(40,321,000)
Extensions, Discoveries, and Other Additions	70,072,000	122,105,000		56,643,000
Purchases of Reserves	0	0		19,878,000
Dispositions	(30,341,000)	0		(8,178,000)
Production	0	0		0

[1] Includes estimated reserve data related to our Marcellus Shale assets, which were divested in October 2014. See Note 14, Assets Held for Sale, Divestitures and Discontinued Operations, for additional details related to the divestiture of our Marcellus Shale assets. Total proved reserves included 235,950 MMcf of natural gas, for an aggregate of 39,325 Mboe of crude oil equivalent, related to our Marcellus Shale assets. Total proved developed reserves related to those assets included 53,904 MMcf and 8,984 MBoe, respectively, and proved undeveloped reserves included 182,046 MMcf and 30,341 MBoe, respectively.

[2] Includes estimated reserve data related to our Piceance and NECO assets, which were divested in June 2013. See Note 14, Assets Held for Sale, Divestitures and Discontinued Operations, for additional details related to the divestiture of our Piceance and NECO assets. Total proved reserves include 148 MBbls of crude oil and 83,656 MMcf of natural gas, for an aggregate of 14,091 MBoe of crude oil equivalent related to our Piceance and NECO assets. There were no proved undeveloped reserves attributable to the Piceance and NECO assets as of December 31, 2012.

[3] Includes estimated reserve data related to our Permian Basin assets, which were divested in February 2012. See Note 14, Assets Held for Sale, Divestitures and Discontinued Operations, for additional details related to the divestiture of our Permian Basin assets. Total proved reserves included 7,825 MBbls of crude oil, 6,242 MMcf of natural gas and 1,970 MBbls of NGLs, for an aggregate of 10,835 Mboe of crude oil equivalent, related to our Permian assets. Total proved developed reserves related to those assets included 1,815 MBbls, 1,750 MMcf, 550 MBbls and 2,657 MBoe, respectively, and proved undeveloped reserves included 6,010 MBbls, 4,492 MMcf, 1,420 MBbls and 8,179 MBoe, respectively.