CONDENSED CONSOLIDATING FINANCIAL INFORMATION (Balance Sheets) (Details) - USD ($) $ in Thousands |
Sep. 30, 2020 |
Jun. 30, 2020 |
Mar. 31, 2020 |
Dec. 31, 2019 |
Sep. 30, 2019 |
Jun. 30, 2019 |
Mar. 31, 2019 |
Dec. 31, 2018 |
Current assets: |
|
|
|
|
|
|
|
|
Cash and cash equivalents |
$ 51,043
|
|
|
$ 6,060
|
|
|
|
|
Accounts receivable - oil and natural gas sales |
92,443
|
|
|
121,210
|
|
|
|
|
Accounts receivable - joint interest and other |
15,421
|
|
|
47,975
|
|
|
|
|
Accounts receivable - intercompany |
0
|
|
|
0
|
|
|
|
|
Prepaid expenses and other current assets |
51,187
|
|
|
4,431
|
|
|
|
|
Short-term derivative instruments |
6,245
|
|
|
126,201
|
|
|
|
|
Current assets |
216,339
|
|
|
305,877
|
|
|
|
|
Property and equipment: |
|
|
|
|
|
|
|
|
Oil and natural gas properties |
10,786,305
|
|
|
10,595,735
|
|
|
|
|
Other property and equipment |
95,921
|
|
|
96,719
|
|
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
(8,779,704)
|
|
|
(7,228,660)
|
|
|
|
|
Property and equipment, net |
2,102,522
|
|
|
3,463,794
|
|
|
|
|
Other assets: |
|
|
|
|
|
|
|
|
Equity investments and investments in subsidiaries |
16,560
|
|
|
32,044
|
|
|
|
|
Long-term derivative instruments |
1,098
|
|
|
563
|
|
|
|
|
Deferred tax asset |
0
|
|
|
7,563
|
|
|
|
|
Operating lease assets |
2,012
|
|
|
14,168
|
|
|
|
|
Operating lease assets—related parties |
0
|
|
|
43,270
|
|
|
|
|
Other assets |
37,028
|
|
|
15,540
|
|
|
|
|
Total other assets |
56,698
|
|
|
113,148
|
|
|
|
|
Total assets |
2,375,559
|
|
|
3,882,819
|
|
|
|
|
Current liabilities: |
|
|
|
|
|
|
|
|
Accounts payable and accrued liabilities |
295,359
|
|
|
415,218
|
|
|
|
|
Accounts payable - intercompany |
0
|
|
|
0
|
|
|
|
|
Short-term derivative instruments |
24,164
|
|
|
303
|
|
|
|
|
Current portion of operating lease liabilities |
1,757
|
|
|
13,826
|
|
|
|
|
Current portion of operating lease liabilities—related parties |
0
|
|
|
21,220
|
|
|
|
|
Current maturities of long-term debt |
656
|
|
|
631
|
|
|
|
|
Current liabilities |
321,936
|
|
|
451,198
|
|
|
|
|
Long-term derivative instruments |
63,803
|
|
|
53,135
|
|
|
|
|
Asset retirement obligation - long-term |
62,935
|
|
|
60,355
|
|
|
|
|
Uncertain tax position liability |
3,371
|
|
|
3,127
|
|
|
|
|
Non-current operating lease liabilities |
255
|
|
|
342
|
|
|
|
|
Non-current operating lease liabilities—related parties |
0
|
|
|
22,050
|
|
|
|
|
Long-term debt, net of current maturities |
2,068,036
|
|
|
1,978,020
|
|
|
|
|
Total liabilities |
2,520,336
|
|
|
2,568,227
|
|
|
|
|
Stockholders’ equity: |
|
|
|
|
|
|
|
|
Common stock |
1,607
|
|
|
1,597
|
|
|
|
|
Paid-in capital |
4,212,241
|
|
|
4,207,554
|
|
|
|
|
Accumulated other comprehensive loss |
(51,330)
|
|
|
(46,833)
|
|
|
|
|
Accumulated deficit |
(4,307,295)
|
|
|
(2,847,726)
|
|
|
|
|
Total stockholders’ equity |
(144,777)
|
$ 231,340
|
$ 784,049
|
1,314,592
|
$ 3,123,104
|
$ 3,607,408
|
$ 3,368,266
|
$ 3,327,768
|
Total liabilities and stockholders’ equity |
2,375,559
|
|
|
3,882,819
|
|
|
|
|
Reportable Legal Entities | Parent |
|
|
|
|
|
|
|
|
Current assets: |
|
|
|
|
|
|
|
|
Cash and cash equivalents |
43,774
|
|
|
2,768
|
|
|
|
|
Accounts receivable - oil and natural gas sales |
861
|
|
|
859
|
|
|
|
|
Accounts receivable - joint interest and other |
428
|
|
|
5,279
|
|
|
|
|
Accounts receivable - intercompany |
332,011
|
|
|
1,065,593
|
|
|
|
|
Prepaid expenses and other current assets |
18,192
|
|
|
4,047
|
|
|
|
|
Short-term derivative instruments |
6,245
|
|
|
126,201
|
|
|
|
|
Current assets |
401,511
|
|
|
1,204,747
|
|
|
|
|
Property and equipment: |
|
|
|
|
|
|
|
|
Oil and natural gas properties |
1,248,836
|
|
|
1,314,933
|
|
|
|
|
Other property and equipment |
92,551
|
|
|
92,650
|
|
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
(1,425,619)
|
|
|
(1,418,888)
|
|
|
|
|
Property and equipment, net |
(84,232)
|
|
|
(11,305)
|
|
|
|
|
Other assets: |
|
|
|
|
|
|
|
|
Equity investments and investments in subsidiaries |
1,802,762
|
|
|
3,064,503
|
|
|
|
|
Long-term derivative instruments |
1,098
|
|
|
563
|
|
|
|
|
Deferred tax asset |
|
|
|
7,563
|
|
|
|
|
Operating lease assets |
2,012
|
|
|
14,168
|
|
|
|
|
Operating lease assets—related parties |
|
|
|
43,270
|
|
|
|
|
Other assets |
28,390
|
|
|
10,026
|
|
|
|
|
Total other assets |
1,834,262
|
|
|
3,140,093
|
|
|
|
|
Total assets |
2,151,541
|
|
|
4,333,535
|
|
|
|
|
Current liabilities: |
|
|
|
|
|
|
|
|
Accounts payable and accrued liabilities |
59,543
|
|
|
48,006
|
|
|
|
|
Accounts payable - intercompany |
74,733
|
|
|
878,283
|
|
|
|
|
Short-term derivative instruments |
24,164
|
|
|
303
|
|
|
|
|
Current portion of operating lease liabilities |
1,757
|
|
|
13,826
|
|
|
|
|
Current portion of operating lease liabilities—related parties |
|
|
|
21,220
|
|
|
|
|
Current maturities of long-term debt |
656
|
|
|
631
|
|
|
|
|
Current liabilities |
160,853
|
|
|
962,269
|
|
|
|
|
Long-term derivative instruments |
63,803
|
|
|
53,135
|
|
|
|
|
Asset retirement obligation - long-term |
0
|
|
|
0
|
|
|
|
|
Uncertain tax position liability |
3,371
|
|
|
3,127
|
|
|
|
|
Non-current operating lease liabilities |
255
|
|
|
342
|
|
|
|
|
Non-current operating lease liabilities—related parties |
|
|
|
22,050
|
|
|
|
|
Long-term debt, net of current maturities |
2,068,036
|
|
|
1,978,020
|
|
|
|
|
Total liabilities |
2,296,318
|
|
|
3,018,943
|
|
|
|
|
Stockholders’ equity: |
|
|
|
|
|
|
|
|
Common stock |
1,607
|
|
|
1,597
|
|
|
|
|
Paid-in capital |
4,212,241
|
|
|
4,207,554
|
|
|
|
|
Accumulated other comprehensive loss |
(51,329)
|
|
|
(46,833)
|
|
|
|
|
Accumulated deficit |
(4,307,296)
|
|
|
(2,847,726)
|
|
|
|
|
Total stockholders’ equity |
(144,777)
|
|
|
1,314,592
|
|
|
|
|
Total liabilities and stockholders’ equity |
2,151,541
|
|
|
4,333,535
|
|
|
|
|
Reportable Legal Entities | Guarantors |
|
|
|
|
|
|
|
|
Current assets: |
|
|
|
|
|
|
|
|
Cash and cash equivalents |
2,197
|
|
|
3,097
|
|
|
|
|
Accounts receivable - oil and natural gas sales |
91,582
|
|
|
120,351
|
|
|
|
|
Accounts receivable - joint interest and other |
14,993
|
|
|
42,696
|
|
|
|
|
Accounts receivable - intercompany |
73,885
|
|
|
843,223
|
|
|
|
|
Prepaid expenses and other current assets |
32,919
|
|
|
308
|
|
|
|
|
Short-term derivative instruments |
0
|
|
|
0
|
|
|
|
|
Current assets |
215,576
|
|
|
1,009,675
|
|
|
|
|
Property and equipment: |
|
|
|
|
|
|
|
|
Oil and natural gas properties |
9,531,593
|
|
|
9,273,681
|
|
|
|
|
Other property and equipment |
51
|
|
|
50
|
|
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
(7,352,069)
|
|
|
(5,808,254)
|
|
|
|
|
Property and equipment, net |
2,179,575
|
|
|
3,465,477
|
|
|
|
|
Other assets: |
|
|
|
|
|
|
|
|
Equity investments and investments in subsidiaries |
6,333
|
|
|
6,332
|
|
|
|
|
Long-term derivative instruments |
|
|
|
0
|
|
|
|
|
Deferred tax asset |
|
|
|
0
|
|
|
|
|
Operating lease assets |
0
|
|
|
0
|
|
|
|
|
Operating lease assets—related parties |
|
|
|
0
|
|
|
|
|
Other assets |
8,638
|
|
|
5,514
|
|
|
|
|
Total other assets |
14,971
|
|
|
11,846
|
|
|
|
|
Total assets |
2,410,122
|
|
|
4,486,998
|
|
|
|
|
Current liabilities: |
|
|
|
|
|
|
|
|
Accounts payable and accrued liabilities |
235,778
|
|
|
367,088
|
|
|
|
|
Accounts payable - intercompany |
321,373
|
|
|
1,026,249
|
|
|
|
|
Short-term derivative instruments |
0
|
|
|
0
|
|
|
|
|
Current portion of operating lease liabilities |
0
|
|
|
0
|
|
|
|
|
Current portion of operating lease liabilities—related parties |
|
|
|
0
|
|
|
|
|
Current maturities of long-term debt |
0
|
|
|
0
|
|
|
|
|
Current liabilities |
557,151
|
|
|
1,393,337
|
|
|
|
|
Long-term derivative instruments |
0
|
|
|
0
|
|
|
|
|
Asset retirement obligation - long-term |
62,935
|
|
|
58,322
|
|
|
|
|
Uncertain tax position liability |
0
|
|
|
0
|
|
|
|
|
Non-current operating lease liabilities |
0
|
|
|
0
|
|
|
|
|
Non-current operating lease liabilities—related parties |
|
|
|
0
|
|
|
|
|
Long-term debt, net of current maturities |
0
|
|
|
0
|
|
|
|
|
Total liabilities |
620,086
|
|
|
1,451,659
|
|
|
|
|
Stockholders’ equity: |
|
|
|
|
|
|
|
|
Common stock |
0
|
|
|
0
|
|
|
|
|
Paid-in capital |
4,291,981
|
|
|
4,171,408
|
|
|
|
|
Accumulated other comprehensive loss |
3
|
|
|
0
|
|
|
|
|
Accumulated deficit |
(2,501,948)
|
|
|
(1,136,069)
|
|
|
|
|
Total stockholders’ equity |
1,790,036
|
|
|
3,035,339
|
|
|
|
|
Total liabilities and stockholders’ equity |
2,410,122
|
|
|
4,486,998
|
|
|
|
|
Reportable Legal Entities | Non-Guarantors |
|
|
|
|
|
|
|
|
Current assets: |
|
|
|
|
|
|
|
|
Cash and cash equivalents |
5,072
|
|
|
195
|
|
|
|
|
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 |
76
|
|
|
76
|
|
|
|
|
Short-term derivative instruments |
0
|
|
|
0
|
|
|
|
|
Current assets |
5,148
|
|
|
271
|
|
|
|
|
Property and equipment: |
|
|
|
|
|
|
|
|
Oil and natural gas properties |
6,606
|
|
|
7,850
|
|
|
|
|
Other property and equipment |
3,319
|
|
|
4,019
|
|
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
(2,016)
|
|
|
(1,518)
|
|
|
|
|
Property and equipment, net |
7,909
|
|
|
10,351
|
|
|
|
|
Other assets: |
|
|
|
|
|
|
|
|
Equity investments and investments in subsidiaries |
16,521
|
|
|
21,000
|
|
|
|
|
Long-term derivative instruments |
|
|
|
0
|
|
|
|
|
Deferred tax asset |
|
|
|
0
|
|
|
|
|
Operating lease assets |
0
|
|
|
0
|
|
|
|
|
Operating lease assets—related parties |
|
|
|
0
|
|
|
|
|
Other assets |
0
|
|
|
0
|
|
|
|
|
Total other assets |
16,521
|
|
|
21,000
|
|
|
|
|
Total assets |
29,578
|
|
|
31,622
|
|
|
|
|
Current liabilities: |
|
|
|
|
|
|
|
|
Accounts payable and accrued liabilities |
38
|
|
|
124
|
|
|
|
|
Accounts payable - intercompany |
9,789
|
|
|
4,285
|
|
|
|
|
Short-term derivative instruments |
0
|
|
|
0
|
|
|
|
|
Current portion of operating lease liabilities |
0
|
|
|
0
|
|
|
|
|
Current portion of operating lease liabilities—related parties |
|
|
|
0
|
|
|
|
|
Current maturities of long-term debt |
0
|
|
|
0
|
|
|
|
|
Current liabilities |
9,827
|
|
|
4,409
|
|
|
|
|
Long-term derivative instruments |
0
|
|
|
0
|
|
|
|
|
Asset retirement obligation - long-term |
0
|
|
|
2,033
|
|
|
|
|
Uncertain tax position liability |
0
|
|
|
0
|
|
|
|
|
Non-current operating lease liabilities |
0
|
|
|
0
|
|
|
|
|
Non-current operating lease liabilities—related parties |
|
|
|
0
|
|
|
|
|
Long-term debt, net of current maturities |
0
|
|
|
0
|
|
|
|
|
Total liabilities |
9,827
|
|
|
6,442
|
|
|
|
|
Stockholders’ equity: |
|
|
|
|
|
|
|
|
Common stock |
0
|
|
|
0
|
|
|
|
|
Paid-in capital |
267,560
|
|
|
267,557
|
|
|
|
|
Accumulated other comprehensive loss |
(48,902)
|
|
|
(44,763)
|
|
|
|
|
Accumulated deficit |
(198,907)
|
|
|
(197,614)
|
|
|
|
|
Total stockholders’ equity |
19,751
|
|
|
25,180
|
|
|
|
|
Total liabilities and stockholders’ equity |
29,578
|
|
|
31,622
|
|
|
|
|
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 |
(405,896)
|
|
|
(1,908,816)
|
|
|
|
|
Prepaid expenses and other current assets |
0
|
|
|
0
|
|
|
|
|
Short-term derivative instruments |
0
|
|
|
0
|
|
|
|
|
Current assets |
(405,896)
|
|
|
(1,908,816)
|
|
|
|
|
Property and equipment: |
|
|
|
|
|
|
|
|
Oil and natural gas properties |
(730)
|
|
|
(729)
|
|
|
|
|
Other property and equipment |
0
|
|
|
0
|
|
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
0
|
|
|
0
|
|
|
|
|
Property and equipment, net |
(730)
|
|
|
(729)
|
|
|
|
|
Other assets: |
|
|
|
|
|
|
|
|
Equity investments and investments in subsidiaries |
(1,809,056)
|
|
|
(3,059,791)
|
|
|
|
|
Long-term derivative instruments |
|
|
|
0
|
|
|
|
|
Deferred tax asset |
|
|
|
0
|
|
|
|
|
Operating lease assets |
0
|
|
|
0
|
|
|
|
|
Operating lease assets—related parties |
|
|
|
0
|
|
|
|
|
Other assets |
0
|
|
|
0
|
|
|
|
|
Total other assets |
(1,809,056)
|
|
|
(3,059,791)
|
|
|
|
|
Total assets |
(2,215,682)
|
|
|
(4,969,336)
|
|
|
|
|
Current liabilities: |
|
|
|
|
|
|
|
|
Accounts payable and accrued liabilities |
0
|
|
|
0
|
|
|
|
|
Accounts payable - intercompany |
(405,895)
|
|
|
(1,908,817)
|
|
|
|
|
Short-term derivative instruments |
0
|
|
|
0
|
|
|
|
|
Current portion of operating lease liabilities |
0
|
|
|
0
|
|
|
|
|
Current portion of operating lease liabilities—related parties |
|
|
|
0
|
|
|
|
|
Current maturities of long-term debt |
0
|
|
|
0
|
|
|
|
|
Current liabilities |
(405,895)
|
|
|
(1,908,817)
|
|
|
|
|
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
|
|
|
0
|
|
|
|
|
Non-current operating lease liabilities—related parties |
|
|
|
0
|
|
|
|
|
Long-term debt, net of current maturities |
0
|
|
|
0
|
|
|
|
|
Total liabilities |
(405,895)
|
|
|
(1,908,817)
|
|
|
|
|
Stockholders’ equity: |
|
|
|
|
|
|
|
|
Common stock |
0
|
|
|
0
|
|
|
|
|
Paid-in capital |
(4,559,541)
|
|
|
(4,438,965)
|
|
|
|
|
Accumulated other comprehensive loss |
48,898
|
|
|
44,763
|
|
|
|
|
Accumulated deficit |
2,700,856
|
|
|
1,333,683
|
|
|
|
|
Total stockholders’ equity |
(1,809,787)
|
|
|
(3,060,519)
|
|
|
|
|
Total liabilities and stockholders’ equity |
$ (2,215,682)
|
|
|
$ (4,969,336)
|
|
|
|
|