ASSET IMPAIRMENT - Additional Information (Details) $ in Thousands	3 Months Ended					6 Months Ended	12 Months Ended
	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($) MMBoe	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($) MMBoe	Dec. 31, 2016 USD ($) MMBoe	Dec. 31, 2015 USD ($) MMBoe	Dec. 31, 2014 USD ($) MMBoe	Mar. 31, 2014 USD ($)
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment							$ 220,652	$ 1,292,308	$ 416,801
Increase (decrease) in commodity price assumptions (in percentage)							3.00%
Price curve, term							5 years
Proved developed reserves at end of period (in mmboe) | MMBoe		184				264.5	162.1	184	264.5
Assets impairments from discontinued operations							$ 0	$ 0	$ 1,936
Permian Basin unproved leasehold properties
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment	$ 208,300
Central Basin Platform
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment							187,043	484,848	0
Midland Basin
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment						$ 25,800	0	0	25,776
Delaware Basin
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment						$ 90,600	21,288	607,303	90,594
Permian Basin Unproved Leasehold Properties
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment							4,762	29,168	64,361
Permian Basin Unproved Leasehold Properties, Expiration
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment									55,100
San Juan Basin properties
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment	$ 7,500						7,519	$ 133,055	$ 230,315
Proved developed reserves at end of period (in mmboe) | MMBoe		16,930				69,038		16,930	69,038
San Juan Proved and Unproved Properties
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment		$ 133,100
San Juan Basin unproved leasehold properties
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment							40	$ 37,934	$ 5,755
North Louisiana/East Texas
Impaired Long-Lived Assets Held and Used [Line Items]
Sales price										$ 30,300
Assets impairments from discontinued operations							$ 0	0	$ 1,936
Oil Reserves
Impaired Long-Lived Assets Held and Used [Line Items]
Increase (decrease) in commodity price assumptions (in percentage)	(5.00%)		(12.00%)	(19.00%)
Oil Reserves | Permian Basin unproved leasehold properties
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment		$ 646,100	$ 390,200		$ 4,300			$ 1,092,200
Oil Reserves | Central Basin Platform
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment				$ 51,500
Natural Gas
Impaired Long-Lived Assets Held and Used [Line Items]
Increase (decrease) in commodity price assumptions (in percentage)	(4.00%)		(6.00%)	(12.00%)