SUPPLEMENTAL INFORMATION - NATURAL GAS AND CRUDE OIL PROPERTIES Schedule of Developed and Undeveloped Reserves (Unaudited) (Details) bbl in Thousands, Boe in Millions	12 Months Ended
	Dec. 31, 2016 Rate	Dec. 31, 2015 Boe Rate bbl	Dec. 31, 2014 Boe Rate bbl	Dec. 31, 2013 Rate bbl		Dec. 31, 2012 bbl
Schedule of Developed and Undeveloped Reserves [Line Items]
Proved Developed and Undeveloped Reserves, Net		272,825	250,129	265,774		192,810
Undeveloped Reserves Converted to Developed		0	0	0
Revisions of Previous Estimates		(93,471)	(64,825)	(46,480)
Extensions, Discoveries, and Other Additions		131,494	98,029	141,935
Purchases of Reserves		76	17	1,043
Dispositions		(34)	(39,572)	(16,104)
Production		(15,369)	(9,294)	(7,430)
Crude Oil Equivalent (Boe)
Schedule of Developed and Undeveloped Reserves [Line Items]
Proved Developed and Undeveloped Reserves, Net		272,825	250,129	265,774	[1]	192,810	[2]
Revisions of Previous Estimates		(93,471)	(64,825)	(46,480)
Extensions, Discoveries, and Other Additions		131,494	98,029	141,935
Purchases of Reserves		76	17	1,043
Dispositions		(34)	(39,572)	(16,104)
Production		(15,369)	(9,294)	(7,430)
Year-over-Year Activity [Domain]
Schedule of Developed and Undeveloped Reserves [Line Items]
Undeveloped Reserves Converted to Developed		29,000	13,000	3,000
Revisions of Previous Estimates		93,000	(65,000)	46,000
Extensions, Discoveries, and Other Additions		131,000	98,000	142,000
Wells Per Section		16
Gross PUD horizontal locations		791	774
Purchases of Reserves				1,000
Dispositions			(40,000)	(16,000)
Increase (decrease) in proved reserves | Boe		23	(16)
Estimated PUD conversion rate | Rate		16.00%	7.00%	15.00%
Actual PUD conversion rate | Rate	19.00%	17.00%	7.00%	3.00%
Majority of downward revision of our previous estimate of proved reserves				(55,000)
Change in drilling plans		(56,000)	(55,000)
Upward (Downward) Revision due to change in SEC pricing		(33,000)
Upward (Downward) Revision due to removal of re-fracs		(11,000)
Upward (downward) revision due to geological findings		(22,000)
Downward revisions due to adjustments in previous PUD well spacing plans			(2,000)	(32,000)
Downward revisions in reserves due to our shift from vertical to horizontal drilling				(11,000)
Downward revisions Wattenberg Field related to PUDs that are no longer in our core drilling area		(8,000)		(3,000)
Reserve discoveries from non-PUD drilling			16,000	17,000
Extension and discoveries due to adjustments in wells spacing in Wattenberg Field and Marcellus Shale			78,000	125,000
Extension and discoveries in the Marcellus Shale				18,000
Extension and discoveries in the Utica Shale			2,000	14,000
Reserve discoveries, refracs not added in prior year report			2,000
Reserve discoveries, Wattenberg Field				110,000
Developed [Member]
Schedule of Developed and Undeveloped Reserves [Line Items]
Proved Developed and Undeveloped Reserves, Net		70,496	74,905	75,553		81,753
Undeveloped Reserves Converted to Developed		29,090	12,730	3,212
Revisions of Previous Estimates		(26,875)	(22,827)	(6,751)
Extensions, Discoveries, and Other Additions		8,703	27,957	19,830
Purchases of Reserves		76	17	1,043
Dispositions		(34)	(9,231)	(16,104)
Production		(15,369)	(9,294)	(7,430)
Undeveloped [Member]
Schedule of Developed and Undeveloped Reserves [Line Items]
Proved Developed and Undeveloped Reserves, Net		202,329	175,224	190,221		111,057
Undeveloped Reserves Converted to Developed		(29,090)	(12,730)	(3,212)
Revisions of Previous Estimates		(66,596)	(41,998)	(39,729)
Extensions, Discoveries, and Other Additions		122,791	70,072	122,105
Purchases of Reserves		0	0	0
Dispositions		0	(30,341)	0
Production		0	0	0

[1] Includes estimated reserve data related to our Marcellus Shale assets, which were divested in October 2014. See Note 15, 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 15, 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.