BASIS OF PRESENTATION - Components of Oil, Gas, and NGL Sales (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Total oil, gas, and NGL sales	$ 556,274	$ 456,452	$ 1,123,408	$ 903,628
Transportation, processing, and other operating costs	51,933	58,624	97,098	113,647
Total
Disaggregation of Revenue [Line Items]
Total oil, gas, and NGL sales	544,386	445,813	1,099,827	882,250
Oil sales
Disaggregation of Revenue [Line Items]
Total oil, gas, and NGL sales	342,184	232,453	693,907	456,519
Gas sales
Disaggregation of Revenue [Line Items]
Total oil, gas, and NGL sales	80,787	132,474	190,508	264,419
NGL sales
Disaggregation of Revenue [Line Items]
Total oil, gas, and NGL sales	121,415	$ 80,886	215,412	$ 161,312
Pre- ASC 606 Adoption
Disaggregation of Revenue [Line Items]
Transportation, processing, and other operating costs	59,584		119,321
Pre- ASC 606 Adoption | Total
Disaggregation of Revenue [Line Items]
Total oil, gas, and NGL sales	552,037		1,122,050
Pre- ASC 606 Adoption | Oil sales
Disaggregation of Revenue [Line Items]
Total oil, gas, and NGL sales	342,184		693,907
Pre- ASC 606 Adoption | Gas sales
Disaggregation of Revenue [Line Items]
Total oil, gas, and NGL sales	84,727		197,404
Pre- ASC 606 Adoption | NGL sales
Disaggregation of Revenue [Line Items]
Total oil, gas, and NGL sales	125,126		230,739
Accounting Standards Update 2014-09 | Impact of ASC 606
Disaggregation of Revenue [Line Items]
Transportation, processing, and other operating costs	(7,651)		(22,223)
Accounting Standards Update 2014-09 | Impact of ASC 606 | Total
Disaggregation of Revenue [Line Items]
Total oil, gas, and NGL sales	(7,651)		(22,223)
Accounting Standards Update 2014-09 | Impact of ASC 606 | Oil sales
Disaggregation of Revenue [Line Items]
Total oil, gas, and NGL sales	0		0
Accounting Standards Update 2014-09 | Impact of ASC 606 | Gas sales
Disaggregation of Revenue [Line Items]
Total oil, gas, and NGL sales	(3,940)		(6,896)
Accounting Standards Update 2014-09 | Impact of ASC 606 | NGL sales
Disaggregation of Revenue [Line Items]
Total oil, gas, and NGL sales	$ (3,711)		$ (15,327)