Condensed Consolidating Financial Statements (Condensed Consolidating Balance Sheets) (Details) - USD ($) $ in Thousands |
Sep. 30, 2016 |
Dec. 31, 2015 |
Sep. 30, 2015 |
Dec. 31, 2014 |
Current assets: |
|
|
|
|
Cash and cash equivalents |
$ 364,276
|
$ 112,974
|
$ 228,111
|
$ 142,340
|
Accounts receivable—oil and gas |
127,788
|
71,872
|
|
|
Accounts receivable - related parties |
96
|
16
|
|
|
Accounts receivable - intercompany |
|
0
|
|
|
Prepaid expenses and other current assets |
10,740
|
3,905
|
|
|
Short-term derivative instruments |
39,363
|
142,794
|
|
|
Deferred tax asset |
38
|
0
|
|
|
Total current assets |
542,301
|
331,561
|
|
|
Property and equipment: |
|
|
|
|
Oil and natural gas properties |
5,816,458
|
5,424,342
|
|
|
Other property and equipment |
54,460
|
33,171
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
(3,613,662)
|
(2,829,110)
|
|
|
Property and equipment, net |
2,257,256
|
2,628,403
|
|
|
Other assets: |
|
|
|
|
Equity investments |
251,309
|
242,393
|
|
|
Long-term derivative instruments |
15,262
|
51,088
|
|
|
Deferred tax asset |
4,203
|
74,925
|
|
|
Other assets |
5,512
|
6,364
|
|
|
Total other assets |
276,286
|
374,770
|
|
|
Total assets |
3,075,843
|
3,334,734
|
|
|
Current liabilities: |
|
|
|
|
Accounts payable and accrued liabilities |
304,341
|
265,128
|
|
|
Accounts payable - intercompany |
0
|
0
|
|
|
Asset retirement obligation—current |
75
|
75
|
75
|
|
Short-term derivative instruments |
37,220
|
437
|
|
|
Deferred tax liability |
0
|
50,697
|
|
|
Current maturities of long-term debt |
220
|
179
|
|
|
Total current liabilities |
341,856
|
316,516
|
|
|
Long-term derivative instrument |
14,907
|
6,935
|
|
|
Asset retirement obligation—long-term |
32,910
|
26,362
|
23,073
|
|
Long-term debt |
961,050
|
946,084
|
|
|
Total liabilities |
1,350,723
|
1,295,897
|
|
|
Stockholders’ equity: |
|
|
|
|
Common stock |
1,253
|
1,082
|
|
|
Paid-in capital |
3,245,393
|
2,824,303
|
|
|
Accumulated other comprehensive (loss) income |
(50,816)
|
(55,177)
|
|
|
Retained (deficit) earnings |
(1,470,710)
|
(731,371)
|
|
|
Total stockholders’ equity |
1,725,120
|
2,038,837
|
2,871,130
|
2,296,296
|
Total liabilities and stockholders’ equity |
3,075,843
|
3,334,734
|
|
|
Parent |
|
|
|
|
Current assets: |
|
|
|
|
Cash and cash equivalents |
363,279
|
112,494
|
226,161
|
141,535
|
Accounts receivable—oil and gas |
133,159
|
72,241
|
|
|
Accounts receivable - related parties |
96
|
16
|
|
|
Accounts receivable - intercompany |
384,280
|
326,475
|
|
|
Prepaid expenses and other current assets |
10,270
|
3,905
|
|
|
Short-term derivative instruments |
39,363
|
142,794
|
|
|
Deferred tax asset |
38
|
|
|
|
Total current assets |
930,485
|
657,925
|
|
|
Property and equipment: |
|
|
|
|
Oil and natural gas properties |
5,425,128
|
5,108,258
|
|
|
Other property and equipment |
54,417
|
33,128
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
(3,613,630)
|
(2,829,081)
|
|
|
Property and equipment, net |
1,865,915
|
2,312,305
|
|
|
Other assets: |
|
|
|
|
Equity investments |
241,342
|
231,892
|
|
|
Long-term derivative instruments |
15,262
|
51,088
|
|
|
Deferred tax asset |
4,203
|
74,925
|
|
|
Other assets |
5,512
|
6,364
|
|
|
Total other assets |
266,319
|
364,269
|
|
|
Total assets |
3,062,719
|
3,334,499
|
|
|
Current liabilities: |
|
|
|
|
Accounts payable and accrued liabilities |
291,217
|
264,893
|
|
|
Accounts payable - intercompany |
0
|
0
|
|
|
Asset retirement obligation—current |
75
|
75
|
|
|
Short-term derivative instruments |
37,220
|
437
|
|
|
Deferred tax liability |
|
50,697
|
|
|
Current maturities of long-term debt |
220
|
179
|
|
|
Total current liabilities |
328,732
|
316,281
|
|
|
Long-term derivative instrument |
14,907
|
6,935
|
|
|
Asset retirement obligation—long-term |
32,910
|
26,362
|
|
|
Long-term debt |
961,050
|
946,084
|
|
|
Total liabilities |
1,337,599
|
1,295,662
|
|
|
Stockholders’ equity: |
|
|
|
|
Common stock |
1,253
|
1,082
|
|
|
Paid-in capital |
3,245,393
|
2,824,303
|
|
|
Accumulated other comprehensive (loss) income |
(50,816)
|
(55,177)
|
|
|
Retained (deficit) earnings |
(1,470,710)
|
(731,371)
|
|
|
Total stockholders’ equity |
1,725,120
|
2,038,837
|
|
|
Total liabilities and stockholders’ equity |
3,062,719
|
3,334,499
|
|
|
Guarantors |
|
|
|
|
Current assets: |
|
|
|
|
Cash and cash equivalents |
996
|
479
|
1,949
|
804
|
Accounts receivable—oil and gas |
16,283
|
54
|
|
|
Accounts receivable - related parties |
0
|
0
|
|
|
Accounts receivable - intercompany |
5,970
|
60
|
|
|
Prepaid expenses and other current assets |
470
|
0
|
|
|
Short-term derivative instruments |
0
|
0
|
|
|
Deferred tax asset |
0
|
|
|
|
Total current assets |
23,719
|
593
|
|
|
Property and equipment: |
|
|
|
|
Oil and natural gas properties |
392,059
|
316,813
|
|
|
Other property and equipment |
43
|
43
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
(32)
|
(29)
|
|
|
Property and equipment, net |
392,070
|
316,827
|
|
|
Other assets: |
|
|
|
|
Equity investments |
26,540
|
0
|
|
|
Long-term derivative instruments |
0
|
0
|
|
|
Deferred tax asset |
0
|
0
|
|
|
Other assets |
|
0
|
|
|
Total other assets |
26,540
|
|
|
|
Total assets |
442,329
|
317,420
|
|
|
Current liabilities: |
|
|
|
|
Accounts payable and accrued liabilities |
40,557
|
527
|
|
|
Accounts payable - intercompany |
384,346
|
326,541
|
|
|
Asset retirement obligation—current |
|
0
|
|
|
Short-term derivative instruments |
|
0
|
|
|
Deferred tax liability |
|
0
|
|
|
Current maturities of long-term debt |
0
|
0
|
|
|
Total current liabilities |
424,903
|
327,068
|
|
|
Long-term derivative instrument |
0
|
0
|
|
|
Asset retirement obligation—long-term |
0
|
0
|
|
|
Long-term debt |
0
|
0
|
|
|
Total liabilities |
424,903
|
327,068
|
|
|
Stockholders’ equity: |
|
|
|
|
Common stock |
|
0
|
|
|
Paid-in capital |
26,822
|
322
|
|
|
Accumulated other comprehensive (loss) income |
|
0
|
|
|
Retained (deficit) earnings |
(9,396)
|
(9,970)
|
|
|
Total stockholders’ equity |
17,426
|
(9,648)
|
|
|
Total liabilities and stockholders’ equity |
442,329
|
317,420
|
|
|
Non-Guarantor |
|
|
|
|
Current assets: |
|
|
|
|
Cash and cash equivalents |
1
|
1
|
1
|
1
|
Accounts receivable—oil and gas |
0
|
0
|
|
|
Accounts receivable - related parties |
0
|
0
|
|
|
Accounts receivable - intercompany |
0
|
0
|
|
|
Prepaid expenses and other current assets |
0
|
0
|
|
|
Short-term derivative instruments |
0
|
0
|
|
|
Deferred tax asset |
0
|
|
|
|
Total current assets |
1
|
1
|
|
|
Property and equipment: |
|
|
|
|
Oil and natural gas properties |
|
0
|
|
|
Other property and equipment |
|
0
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
|
0
|
|
|
Property and equipment, net |
|
0
|
|
|
Other assets: |
|
|
|
|
Equity investments |
48,596
|
50,644
|
|
|
Long-term derivative instruments |
0
|
0
|
|
|
Deferred tax asset |
0
|
0
|
|
|
Other assets |
|
0
|
|
|
Total other assets |
48,596
|
50,644
|
|
|
Total assets |
48,597
|
50,645
|
|
|
Current liabilities: |
|
|
|
|
Accounts payable and accrued liabilities |
1
|
0
|
|
|
Accounts payable - intercompany |
125
|
124
|
|
|
Asset retirement obligation—current |
|
0
|
|
|
Short-term derivative instruments |
|
0
|
|
|
Deferred tax liability |
|
0
|
|
|
Current maturities of long-term debt |
0
|
0
|
|
|
Total current liabilities |
126
|
124
|
|
|
Long-term derivative instrument |
0
|
0
|
|
|
Asset retirement obligation—long-term |
0
|
0
|
|
|
Long-term debt |
0
|
0
|
|
|
Total liabilities |
126
|
124
|
|
|
Stockholders’ equity: |
|
|
|
|
Common stock |
|
0
|
|
|
Paid-in capital |
256,065
|
241,553
|
|
|
Accumulated other comprehensive (loss) income |
(46,925)
|
(55,177)
|
|
|
Retained (deficit) earnings |
(160,669)
|
(135,855)
|
|
|
Total stockholders’ equity |
48,471
|
50,521
|
|
|
Total liabilities and stockholders’ equity |
48,597
|
50,645
|
|
|
Eliminations |
|
|
|
|
Current assets: |
|
|
|
|
Cash and cash equivalents |
0
|
0
|
$ 0
|
$ 0
|
Accounts receivable—oil and gas |
(21,654)
|
(423)
|
|
|
Accounts receivable - related parties |
0
|
0
|
|
|
Accounts receivable - intercompany |
(390,250)
|
(326,535)
|
|
|
Prepaid expenses and other current assets |
|
0
|
|
|
Short-term derivative instruments |
0
|
0
|
|
|
Deferred tax asset |
0
|
|
|
|
Total current assets |
(411,904)
|
(326,958)
|
|
|
Property and equipment: |
|
|
|
|
Oil and natural gas properties |
(729)
|
(729)
|
|
|
Other property and equipment |
|
0
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
|
0
|
|
|
Property and equipment, net |
(729)
|
(729)
|
|
|
Other assets: |
|
|
|
|
Equity investments |
(65,169)
|
(40,143)
|
|
|
Long-term derivative instruments |
0
|
0
|
|
|
Deferred tax asset |
0
|
0
|
|
|
Other assets |
|
0
|
|
|
Total other assets |
(65,169)
|
(40,143)
|
|
|
Total assets |
(477,802)
|
(367,830)
|
|
|
Current liabilities: |
|
|
|
|
Accounts payable and accrued liabilities |
(27,434)
|
(292)
|
|
|
Accounts payable - intercompany |
(384,471)
|
(326,665)
|
|
|
Asset retirement obligation—current |
|
0
|
|
|
Short-term derivative instruments |
|
0
|
|
|
Deferred tax liability |
|
0
|
|
|
Current maturities of long-term debt |
0
|
0
|
|
|
Total current liabilities |
(411,905)
|
(326,957)
|
|
|
Long-term derivative instrument |
0
|
0
|
|
|
Asset retirement obligation—long-term |
0
|
0
|
|
|
Long-term debt |
0
|
0
|
|
|
Total liabilities |
(411,905)
|
(326,957)
|
|
|
Stockholders’ equity: |
|
|
|
|
Common stock |
|
0
|
|
|
Paid-in capital |
(282,887)
|
(241,875)
|
|
|
Accumulated other comprehensive (loss) income |
46,925
|
55,177
|
|
|
Retained (deficit) earnings |
170,065
|
145,825
|
|
|
Total stockholders’ equity |
(65,897)
|
(40,873)
|
|
|
Total liabilities and stockholders’ equity |
$ (477,802)
|
$ (367,830)
|
|
|