CONDENSED CONSOLIDATING FINANCIAL INFORMATION (Balance Sheets) (Details) - USD ($) $ in Thousands |
Sep. 30, 2019 |
Jun. 30, 2019 |
Mar. 31, 2019 |
Dec. 31, 2018 |
Sep. 30, 2018 |
Jun. 30, 2018 |
Mar. 31, 2018 |
Dec. 31, 2017 |
Current assets: |
|
|
|
|
|
|
|
|
Cash and cash equivalents |
$ 10,124
|
|
|
$ 52,297
|
|
|
|
|
Accounts receivable - oil and natural gas sales |
112,657
|
|
|
210,200
|
|
|
|
|
Accounts receivable - joint interest and other |
41,327
|
|
|
22,497
|
|
|
|
|
Accounts receivable - intercompany |
0
|
|
|
0
|
|
|
|
|
Prepaid expenses and other current assets |
5,658
|
|
|
10,017
|
|
|
|
|
Short-term derivative instruments |
134,571
|
|
|
21,352
|
|
|
|
|
Total current assets |
304,337
|
|
|
316,363
|
|
|
|
|
Property and equipment: |
|
|
|
|
|
|
|
|
Oil and natural gas properties |
10,551,713
|
|
|
10,026,836
|
|
|
|
|
Other property and equipment |
96,233
|
|
|
92,667
|
|
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
(5,063,413)
|
|
|
(4,640,098)
|
|
|
|
|
Property and equipment, net |
5,584,533
|
|
|
5,479,405
|
|
|
|
|
Other assets: |
|
|
|
|
|
|
|
|
Equity investments and investments in subsidiaries |
73,962
|
|
|
236,121
|
|
|
|
|
Long-term derivative instruments |
23,419
|
|
|
0
|
|
|
|
|
Deferred tax asset |
205,853
|
|
|
0
|
|
|
|
|
Inventories |
7,022
|
|
|
5,344
|
|
|
|
|
Operating lease assets |
13,920
|
|
|
|
|
|
|
|
Operating lease assets - related parties |
48,449
|
|
|
|
|
|
|
|
Other assets |
11,653
|
|
|
13,803
|
|
|
|
|
Total other assets |
384,278
|
|
|
255,268
|
|
|
|
|
Total assets |
6,273,148
|
|
|
6,051,036
|
|
|
|
|
Current liabilities: |
|
|
|
|
|
|
|
|
Accounts payable and accrued liabilities |
439,019
|
|
|
518,380
|
|
|
|
|
Accounts payable - intercompany |
0
|
|
|
0
|
|
|
|
|
Short-term derivative instruments |
429
|
|
|
20,401
|
|
|
|
|
Current portion of operating lease liabilities |
12,848
|
|
|
|
|
|
|
|
Current portion of operating lease liabilities - related parties |
21,017
|
|
|
|
|
|
|
|
Current maturities of long-term debt |
622
|
|
|
651
|
|
|
|
|
Total current liabilities |
473,935
|
|
|
539,432
|
|
|
|
|
Long-term derivative instruments |
72,040
|
|
|
13,992
|
|
|
|
|
Asset retirement obligation—long-term |
59,819
|
|
|
79,952
|
$ 78,411
|
|
|
|
Uncertain tax position liability |
3,127
|
|
|
3,127
|
|
|
|
|
Non-current operating lease liabilities |
1,072
|
|
|
|
|
|
|
|
Non-current operating lease liabilities - related parties |
27,432
|
|
|
|
|
|
|
|
Long-term debt, net of current maturities |
2,076,569
|
|
|
2,086,765
|
|
|
|
|
Total liabilities |
2,713,994
|
|
|
2,723,268
|
|
|
|
|
Stockholders’ equity: |
|
|
|
|
|
|
|
|
Common stock |
1,597
|
|
|
1,630
|
|
|
|
|
Paid-in capital |
4,205,158
|
|
|
4,227,532
|
|
|
|
|
Accumulated other comprehensive loss |
(50,679)
|
|
|
(56,026)
|
|
|
|
|
(Accumulated deficit) retained earnings |
(596,922)
|
|
|
(845,368)
|
|
|
|
|
Total stockholders’ equity |
3,559,154
|
$ 3,607,408
|
$ 3,368,266
|
3,327,768
|
$ 3,292,015
|
$ 3,195,199
|
$ 3,088,889
|
$ 3,101,614
|
Total liabilities and stockholders’ equity |
6,273,148
|
|
|
6,051,036
|
|
|
|
|
Reportable legal entities | Parent |
|
|
|
|
|
|
|
|
Current assets: |
|
|
|
|
|
|
|
|
Cash and cash equivalents |
6,279
|
|
|
25,585
|
|
|
|
|
Accounts receivable - oil and natural gas sales |
857
|
|
|
146,075
|
|
|
|
|
Accounts receivable - joint interest and other |
6,909
|
|
|
16,212
|
|
|
|
|
Accounts receivable - intercompany |
953,446
|
|
|
671,633
|
|
|
|
|
Prepaid expenses and other current assets |
3,886
|
|
|
7,843
|
|
|
|
|
Short-term derivative instruments |
134,571
|
|
|
21,352
|
|
|
|
|
Total current assets |
1,105,948
|
|
|
888,700
|
|
|
|
|
Property and equipment: |
|
|
|
|
|
|
|
|
Oil and natural gas properties |
1,312,715
|
|
|
7,044,550
|
|
|
|
|
Other property and equipment |
92,163
|
|
|
91,916
|
|
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
(1,416,261)
|
|
|
(4,640,059)
|
|
|
|
|
Property and equipment, net |
(11,383)
|
|
|
2,496,407
|
|
|
|
|
Other assets: |
|
|
|
|
|
|
|
|
Equity investments and investments in subsidiaries |
5,106,904
|
|
|
2,856,988
|
|
|
|
|
Long-term derivative instruments |
23,419
|
|
|
|
|
|
|
|
Deferred tax asset |
205,853
|
|
|
|
|
|
|
|
Inventories |
94
|
|
|
4,210
|
|
|
|
|
Operating lease assets |
13,920
|
|
|
|
|
|
|
|
Operating lease assets - related parties |
48,449
|
|
|
|
|
|
|
|
Other assets |
11,333
|
|
|
12,624
|
|
|
|
|
Total other assets |
5,409,972
|
|
|
2,873,822
|
|
|
|
|
Total assets |
6,504,537
|
|
|
6,258,929
|
|
|
|
|
Current liabilities: |
|
|
|
|
|
|
|
|
Accounts payable and accrued liabilities |
69,863
|
|
|
419,107
|
|
|
|
|
Accounts payable - intercompany |
660,364
|
|
|
320,259
|
|
|
|
|
Short-term derivative instruments |
429
|
|
|
20,401
|
|
|
|
|
Current portion of operating lease liabilities |
12,848
|
|
|
|
|
|
|
|
Current portion of operating lease liabilities - related parties |
21,017
|
|
|
|
|
|
|
|
Current maturities of long-term debt |
622
|
|
|
651
|
|
|
|
|
Total current liabilities |
765,143
|
|
|
760,418
|
|
|
|
|
Long-term derivative instruments |
72,040
|
|
|
13,992
|
|
|
|
|
Asset retirement obligation—long-term |
0
|
|
|
66,859
|
|
|
|
|
Uncertain tax position liability |
3,127
|
|
|
3,127
|
|
|
|
|
Non-current operating lease liabilities |
1,072
|
|
|
|
|
|
|
|
Non-current operating lease liabilities - related parties |
27,432
|
|
|
|
|
|
|
|
Long-term debt, net of current maturities |
2,076,569
|
|
|
2,086,765
|
|
|
|
|
Total liabilities |
2,945,383
|
|
|
2,931,161
|
|
|
|
|
Stockholders’ equity: |
|
|
|
|
|
|
|
|
Common stock |
1,597
|
|
|
1,630
|
|
|
|
|
Paid-in capital |
4,205,158
|
|
|
4,227,532
|
|
|
|
|
Accumulated other comprehensive loss |
(50,679)
|
|
|
(56,026)
|
|
|
|
|
(Accumulated deficit) retained earnings |
(596,922)
|
|
|
(845,368)
|
|
|
|
|
Total stockholders’ equity |
3,559,154
|
|
|
3,327,768
|
|
|
|
|
Total liabilities and stockholders’ equity |
6,504,537
|
|
|
6,258,929
|
|
|
|
|
Reportable legal entities | Guarantors |
|
|
|
|
|
|
|
|
Current assets: |
|
|
|
|
|
|
|
|
Cash and cash equivalents |
3,715
|
|
|
26,711
|
|
|
|
|
Accounts receivable - oil and natural gas sales |
111,800
|
|
|
64,125
|
|
|
|
|
Accounts receivable - joint interest and other |
34,418
|
|
|
6,285
|
|
|
|
|
Accounts receivable - intercompany |
625,306
|
|
|
319,464
|
|
|
|
|
Prepaid expenses and other current assets |
1,697
|
|
|
2,174
|
|
|
|
|
Short-term derivative instruments |
0
|
|
|
0
|
|
|
|
|
Total current assets |
776,936
|
|
|
418,759
|
|
|
|
|
Property and equipment: |
|
|
|
|
|
|
|
|
Oil and natural gas properties |
9,239,581
|
|
|
2,983,015
|
|
|
|
|
Other property and equipment |
751
|
|
|
751
|
|
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
(3,646,931)
|
|
|
(39)
|
|
|
|
|
Property and equipment, net |
5,593,401
|
|
|
2,983,727
|
|
|
|
|
Other assets: |
|
|
|
|
|
|
|
|
Equity investments and investments in subsidiaries |
|
|
|
0
|
|
|
|
|
Long-term derivative instruments |
0
|
|
|
|
|
|
|
|
Deferred tax asset |
0
|
|
|
|
|
|
|
|
Inventories |
6,928
|
|
|
1,134
|
|
|
|
|
Operating lease assets |
0
|
|
|
|
|
|
|
|
Operating lease assets - related parties |
0
|
|
|
|
|
|
|
|
Other assets |
320
|
|
|
1,178
|
|
|
|
|
Total other assets |
7,248
|
|
|
2,312
|
|
|
|
|
Total assets |
6,377,585
|
|
|
3,404,798
|
|
|
|
|
Current liabilities: |
|
|
|
|
|
|
|
|
Accounts payable and accrued liabilities |
369,129
|
|
|
99,273
|
|
|
|
|
Accounts payable - intercompany |
914,401
|
|
|
670,708
|
|
|
|
|
Short-term derivative instruments |
0
|
|
|
0
|
|
|
|
|
Current portion of operating lease liabilities |
0
|
|
|
|
|
|
|
|
Current portion of operating lease liabilities - related parties |
0
|
|
|
|
|
|
|
|
Current maturities of long-term debt |
0
|
|
|
0
|
|
|
|
|
Total current liabilities |
1,283,530
|
|
|
769,981
|
|
|
|
|
Long-term derivative instruments |
0
|
|
|
0
|
|
|
|
|
Asset retirement obligation—long-term |
59,819
|
|
|
13,093
|
|
|
|
|
Uncertain tax position liability |
0
|
|
|
0
|
|
|
|
|
Non-current operating lease liabilities |
0
|
|
|
|
|
|
|
|
Non-current operating lease liabilities - related parties |
0
|
|
|
|
|
|
|
|
Long-term debt, net of current maturities |
0
|
|
|
0
|
|
|
|
|
Total liabilities |
1,343,349
|
|
|
783,074
|
|
|
|
|
Stockholders’ equity: |
|
|
|
|
|
|
|
|
Common stock |
0
|
|
|
0
|
|
|
|
|
Paid-in capital |
4,170,573
|
|
|
1,915,598
|
|
|
|
|
Accumulated other comprehensive loss |
0
|
|
|
0
|
|
|
|
|
(Accumulated deficit) retained earnings |
863,663
|
|
|
706,126
|
|
|
|
|
Total stockholders’ equity |
5,034,236
|
|
|
2,621,724
|
|
|
|
|
Total liabilities and stockholders’ equity |
6,377,585
|
|
|
3,404,798
|
|
|
|
|
Reportable legal entities | Non-Guarantors |
|
|
|
|
|
|
|
|
Current assets: |
|
|
|
|
|
|
|
|
Cash and cash equivalents |
130
|
|
|
1
|
|
|
|
|
Accounts receivable - oil and natural gas sales |
0
|
|
|
0
|
|
|
|
|
Accounts receivable - joint interest and other |
0
|
|
|
0
|
|
|
|
|
Accounts receivable - intercompany |
0
|
|
|
0
|
|
|
|
|
Prepaid expenses and other current assets |
75
|
|
|
0
|
|
|
|
|
Short-term derivative instruments |
0
|
|
|
0
|
|
|
|
|
Total current assets |
205
|
|
|
1
|
|
|
|
|
Property and equipment: |
|
|
|
|
|
|
|
|
Oil and natural gas properties |
146
|
|
|
0
|
|
|
|
|
Other property and equipment |
3,319
|
|
|
0
|
|
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
(221)
|
|
|
0
|
|
|
|
|
Property and equipment, net |
3,244
|
|
|
0
|
|
|
|
|
Other assets: |
|
|
|
|
|
|
|
|
Equity investments and investments in subsidiaries |
49,545
|
|
|
44,259
|
|
|
|
|
Long-term derivative instruments |
0
|
|
|
|
|
|
|
|
Deferred tax asset |
0
|
|
|
|
|
|
|
|
Inventories |
0
|
|
|
0
|
|
|
|
|
Operating lease assets |
0
|
|
|
|
|
|
|
|
Operating lease assets - related parties |
0
|
|
|
|
|
|
|
|
Other assets |
0
|
|
|
0
|
|
|
|
|
Total other assets |
49,545
|
|
|
44,259
|
|
|
|
|
Total assets |
52,994
|
|
|
44,260
|
|
|
|
|
Current liabilities: |
|
|
|
|
|
|
|
|
Accounts payable and accrued liabilities |
27
|
|
|
0
|
|
|
|
|
Accounts payable - intercompany |
3,987
|
|
|
130
|
|
|
|
|
Short-term derivative instruments |
0
|
|
|
0
|
|
|
|
|
Current portion of operating lease liabilities |
0
|
|
|
|
|
|
|
|
Current portion of operating lease liabilities - related parties |
0
|
|
|
|
|
|
|
|
Current maturities of long-term debt |
0
|
|
|
0
|
|
|
|
|
Total current liabilities |
4,014
|
|
|
130
|
|
|
|
|
Long-term derivative instruments |
0
|
|
|
0
|
|
|
|
|
Asset retirement obligation—long-term |
0
|
|
|
0
|
|
|
|
|
Uncertain tax position liability |
0
|
|
|
0
|
|
|
|
|
Non-current operating lease liabilities |
0
|
|
|
|
|
|
|
|
Non-current operating lease liabilities - related parties |
0
|
|
|
|
|
|
|
|
Long-term debt, net of current maturities |
0
|
|
|
0
|
|
|
|
|
Total liabilities |
4,014
|
|
|
130
|
|
|
|
|
Stockholders’ equity: |
|
|
|
|
|
|
|
|
Common stock |
0
|
|
|
0
|
|
|
|
|
Paid-in capital |
262,061
|
|
|
261,626
|
|
|
|
|
Accumulated other comprehensive loss |
(48,548)
|
|
|
(53,783)
|
|
|
|
|
(Accumulated deficit) retained earnings |
(164,533)
|
|
|
(163,713)
|
|
|
|
|
Total stockholders’ equity |
48,980
|
|
|
44,130
|
|
|
|
|
Total liabilities and stockholders’ equity |
52,994
|
|
|
44,260
|
|
|
|
|
Eliminations |
|
|
|
|
|
|
|
|
Current assets: |
|
|
|
|
|
|
|
|
Cash and cash equivalents |
0
|
|
|
0
|
|
|
|
|
Accounts receivable - oil and natural gas sales |
0
|
|
|
0
|
|
|
|
|
Accounts receivable - joint interest and other |
0
|
|
|
0
|
|
|
|
|
Accounts receivable - intercompany |
(1,578,752)
|
|
|
(991,097)
|
|
|
|
|
Prepaid expenses and other current assets |
0
|
|
|
0
|
|
|
|
|
Short-term derivative instruments |
0
|
|
|
0
|
|
|
|
|
Total current assets |
(1,578,752)
|
|
|
(991,097)
|
|
|
|
|
Property and equipment: |
|
|
|
|
|
|
|
|
Oil and natural gas properties |
(729)
|
|
|
(729)
|
|
|
|
|
Other property and equipment |
0
|
|
|
0
|
|
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
0
|
|
|
0
|
|
|
|
|
Property and equipment, net |
(729)
|
|
|
(729)
|
|
|
|
|
Other assets: |
|
|
|
|
|
|
|
|
Equity investments and investments in subsidiaries |
(5,082,487)
|
|
|
(2,665,126)
|
|
|
|
|
Long-term derivative instruments |
0
|
|
|
|
|
|
|
|
Deferred tax asset |
0
|
|
|
|
|
|
|
|
Inventories |
0
|
|
|
0
|
|
|
|
|
Operating lease assets |
0
|
|
|
|
|
|
|
|
Operating lease assets - related parties |
0
|
|
|
|
|
|
|
|
Other assets |
0
|
|
|
1
|
|
|
|
|
Total other assets |
(5,082,487)
|
|
|
(2,665,125)
|
|
|
|
|
Total assets |
(6,661,968)
|
|
|
(3,656,951)
|
|
|
|
|
Current liabilities: |
|
|
|
|
|
|
|
|
Accounts payable and accrued liabilities |
0
|
|
|
0
|
|
|
|
|
Accounts payable - intercompany |
(1,578,752)
|
|
|
(991,097)
|
|
|
|
|
Short-term derivative instruments |
0
|
|
|
0
|
|
|
|
|
Current portion of operating lease liabilities |
0
|
|
|
|
|
|
|
|
Current portion of operating lease liabilities - related parties |
0
|
|
|
|
|
|
|
|
Current maturities of long-term debt |
0
|
|
|
0
|
|
|
|
|
Total current liabilities |
(1,578,752)
|
|
|
(991,097)
|
|
|
|
|
Long-term derivative instruments |
0
|
|
|
0
|
|
|
|
|
Asset retirement obligation—long-term |
0
|
|
|
0
|
|
|
|
|
Uncertain tax position liability |
0
|
|
|
0
|
|
|
|
|
Non-current operating lease liabilities |
0
|
|
|
|
|
|
|
|
Non-current operating lease liabilities - related parties |
0
|
|
|
|
|
|
|
|
Long-term debt, net of current maturities |
0
|
|
|
0
|
|
|
|
|
Total liabilities |
(1,578,752)
|
|
|
(991,097)
|
|
|
|
|
Stockholders’ equity: |
|
|
|
|
|
|
|
|
Common stock |
0
|
|
|
0
|
|
|
|
|
Paid-in capital |
(4,432,634)
|
|
|
(2,177,224)
|
|
|
|
|
Accumulated other comprehensive loss |
48,548
|
|
|
53,783
|
|
|
|
|
(Accumulated deficit) retained earnings |
(699,130)
|
|
|
(542,413)
|
|
|
|
|
Total stockholders’ equity |
(5,083,216)
|
|
|
(2,665,854)
|
|
|
|
|
Total liabilities and stockholders’ equity |
$ (6,661,968)
|
|
|
$ (3,656,951)
|
|
|
|
|