Condensed Consolidating Financial Information - Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Thousands |
Mar. 31, 2016 |
Dec. 31, 2015 |
Mar. 31, 2015 |
Dec. 31, 2014 |
Current assets: |
|
|
|
|
Cash and cash equivalents |
$ 454,377
|
$ 112,974
|
$ 74,740
|
$ 142,340
|
Accounts receivable—oil and gas |
78,501
|
71,872
|
|
|
Accounts receivable - related parties |
17
|
16
|
|
|
Accounts receivable - intercompany |
|
0
|
|
|
Prepaid expenses and other current assets |
2,755
|
3,905
|
|
|
Short-term derivative instruments |
152,211
|
142,794
|
|
|
Total current assets |
687,861
|
331,561
|
|
|
Property and equipment: |
|
|
|
|
Oil and natural gas properties |
5,506,570
|
5,424,342
|
|
|
Other property and equipment |
40,576
|
33,171
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
(3,112,767)
|
(2,829,110)
|
|
|
Property and equipment, net |
2,434,379
|
2,628,403
|
|
|
Other assets: |
|
|
|
|
Equity investments |
244,601
|
242,393
|
|
|
Long-term derivative instruments |
42,455
|
51,088
|
|
|
Deferred tax asset |
76,327
|
74,925
|
|
|
Other assets |
17,036
|
6,364
|
|
|
Total other assets |
380,419
|
374,770
|
|
|
Total assets |
3,502,659
|
3,334,734
|
|
|
Current liabilities: |
|
|
|
|
Accounts payable and accrued liabilities |
235,834
|
265,128
|
|
|
Accounts payable - intercompany |
0
|
0
|
|
|
Asset retirement obligation—current |
75
|
75
|
75
|
|
Short-term derivative instruments |
5,715
|
437
|
|
|
Deferred tax liability |
51,908
|
50,697
|
|
|
Current maturities of long-term debt |
0
|
179
|
|
|
Total current liabilities |
293,532
|
316,516
|
|
|
Long-term derivative instrument |
10,127
|
6,935
|
|
|
Asset retirement obligation—long-term |
28,471
|
26,362
|
18,656
|
|
Asset retirement obligation - long-term |
|
26,362
|
|
|
Long-term debt |
949,740
|
946,084
|
|
|
Total liabilities |
1,281,870
|
1,295,897
|
|
|
Stockholders’ equity: |
|
|
|
|
Common stock |
1,252
|
1,082
|
|
|
Paid-in capital |
3,239,294
|
2,824,303
|
|
|
Accumulated other comprehensive (loss) income |
(46,119)
|
(55,177)
|
|
|
Retained (deficit) earnings |
(973,638)
|
(731,371)
|
|
|
Total stockholders’ equity |
2,220,789
|
2,038,837
|
2,310,293
|
2,296,296
|
Total liabilities and stockholders’ equity |
3,502,659
|
3,334,734
|
|
|
Parent |
|
|
|
|
Current assets: |
|
|
|
|
Cash and cash equivalents |
453,743
|
112,494
|
73,667
|
141,535
|
Accounts receivable—oil and gas |
78,419
|
72,241
|
|
|
Accounts receivable - related parties |
17
|
16
|
|
|
Accounts receivable - intercompany |
341,062
|
326,475
|
|
|
Prepaid expenses and other current assets |
2,755
|
3,905
|
|
|
Short-term derivative instruments |
152,211
|
142,794
|
|
|
Total current assets |
1,028,207
|
657,925
|
|
|
Property and equipment: |
|
|
|
|
Oil and natural gas properties |
5,174,684
|
5,108,258
|
|
|
Other property and equipment |
40,533
|
33,128
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
(3,112,737)
|
(2,829,081)
|
|
|
Property and equipment, net |
2,102,480
|
2,312,305
|
|
|
Other assets: |
|
|
|
|
Equity investments |
234,063
|
231,892
|
|
|
Long-term derivative instruments |
42,455
|
51,088
|
|
|
Deferred tax asset |
76,327
|
74,925
|
|
|
Other assets |
17,038
|
6,364
|
|
|
Total other assets |
369,883
|
364,269
|
|
|
Total assets |
3,500,570
|
3,334,499
|
|
|
Current liabilities: |
|
|
|
|
Accounts payable and accrued liabilities |
233,745
|
264,893
|
|
|
Accounts payable - intercompany |
0
|
0
|
|
|
Asset retirement obligation—current |
75
|
75
|
|
|
Short-term derivative instruments |
5,715
|
437
|
|
|
Deferred tax liability |
51,908
|
50,697
|
|
|
Current maturities of long-term debt |
|
179
|
|
|
Total current liabilities |
291,443
|
316,281
|
|
|
Long-term derivative instrument |
10,127
|
6,935
|
|
|
Asset retirement obligation—long-term |
28,471
|
|
|
|
Asset retirement obligation - long-term |
|
26,362
|
|
|
Long-term debt |
949,740
|
946,084
|
|
|
Total liabilities |
1,279,781
|
1,295,662
|
|
|
Stockholders’ equity: |
|
|
|
|
Common stock |
1,252
|
1,082
|
|
|
Paid-in capital |
3,239,294
|
2,824,303
|
|
|
Accumulated other comprehensive (loss) income |
(46,119)
|
(55,177)
|
|
|
Retained (deficit) earnings |
(973,638)
|
(731,371)
|
|
|
Total stockholders’ equity |
2,220,789
|
2,038,837
|
|
|
Total liabilities and stockholders’ equity |
3,500,570
|
3,334,499
|
|
|
Guarantors |
|
|
|
|
Current assets: |
|
|
|
|
Cash and cash equivalents |
634
|
479
|
1,072
|
804
|
Accounts receivable—oil and gas |
2,324
|
54
|
|
|
Accounts receivable - related parties |
0
|
0
|
|
|
Accounts receivable - intercompany |
661
|
60
|
|
|
Prepaid expenses and other current assets |
|
0
|
|
|
Short-term derivative instruments |
0
|
0
|
|
|
Total current assets |
3,619
|
593
|
|
|
Property and equipment: |
|
|
|
|
Oil and natural gas properties |
332,615
|
316,813
|
|
|
Other property and equipment |
43
|
43
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
(30)
|
(29)
|
|
|
Property and equipment, net |
332,628
|
316,827
|
|
|
Other assets: |
|
|
|
|
Equity investments |
22,500
|
0
|
|
|
Long-term derivative instruments |
0
|
0
|
|
|
Deferred tax asset |
0
|
0
|
|
|
Other assets |
(2)
|
0
|
|
|
Total other assets |
22,498
|
|
|
|
Total assets |
358,745
|
317,420
|
|
|
Current liabilities: |
|
|
|
|
Accounts payable and accrued liabilities |
4,801
|
527
|
|
|
Accounts payable - intercompany |
341,128
|
326,541
|
|
|
Asset retirement obligation—current |
|
0
|
|
|
Short-term derivative instruments |
|
0
|
|
|
Deferred tax liability |
|
0
|
|
|
Current maturities of long-term debt |
|
0
|
|
|
Total current liabilities |
345,929
|
327,068
|
|
|
Long-term derivative instrument |
0
|
0
|
|
|
Asset retirement obligation—long-term |
0
|
|
|
|
Asset retirement obligation - long-term |
|
0
|
|
|
Long-term debt |
0
|
0
|
|
|
Total liabilities |
345,929
|
327,068
|
|
|
Stockholders’ equity: |
|
|
|
|
Common stock |
|
0
|
|
|
Paid-in capital |
22,822
|
322
|
|
|
Accumulated other comprehensive (loss) income |
|
0
|
|
|
Retained (deficit) earnings |
(10,006)
|
(9,970)
|
|
|
Total stockholders’ equity |
12,816
|
(9,648)
|
|
|
Total liabilities and stockholders’ equity |
358,745
|
317,420
|
|
|
Non-Guarantor |
|
|
|
|
Current assets: |
|
|
|
|
Cash and cash equivalents |
0
|
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
|
|
|
Total current assets |
|
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 |
39,054
|
50,644
|
|
|
Long-term derivative instruments |
0
|
0
|
|
|
Deferred tax asset |
0
|
0
|
|
|
Other assets |
|
0
|
|
|
Total other assets |
39,054
|
50,644
|
|
|
Total assets |
39,054
|
50,645
|
|
|
Current liabilities: |
|
|
|
|
Accounts payable and accrued liabilities |
|
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
|
|
|
Total current liabilities |
125
|
124
|
|
|
Long-term derivative instrument |
0
|
0
|
|
|
Asset retirement obligation—long-term |
0
|
|
|
|
Asset retirement obligation - long-term |
|
0
|
|
|
Long-term debt |
0
|
0
|
|
|
Total liabilities |
125
|
124
|
|
|
Stockholders’ equity: |
|
|
|
|
Common stock |
|
0
|
|
|
Paid-in capital |
243,374
|
241,553
|
|
|
Accumulated other comprehensive (loss) income |
(44,903)
|
(55,177)
|
|
|
Retained (deficit) earnings |
(159,542)
|
(135,855)
|
|
|
Total stockholders’ equity |
38,929
|
50,521
|
|
|
Total liabilities and stockholders’ equity |
39,054
|
50,645
|
|
|
Eliminations |
|
|
|
|
Current assets: |
|
|
|
|
Cash and cash equivalents |
0
|
0
|
$ 0
|
$ 0
|
Accounts receivable—oil and gas |
(2,242)
|
(423)
|
|
|
Accounts receivable - related parties |
0
|
0
|
|
|
Accounts receivable - intercompany |
(341,723)
|
(326,535)
|
|
|
Prepaid expenses and other current assets |
|
0
|
|
|
Short-term derivative instruments |
0
|
0
|
|
|
Total current assets |
(343,965)
|
(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 |
(51,016)
|
(40,143)
|
|
|
Long-term derivative instruments |
0
|
0
|
|
|
Deferred tax asset |
0
|
0
|
|
|
Other assets |
|
0
|
|
|
Total other assets |
(51,016)
|
(40,143)
|
|
|
Total assets |
(395,710)
|
(367,830)
|
|
|
Current liabilities: |
|
|
|
|
Accounts payable and accrued liabilities |
(2,712)
|
(292)
|
|
|
Accounts payable - intercompany |
(341,253)
|
(326,665)
|
|
|
Asset retirement obligation—current |
|
0
|
|
|
Short-term derivative instruments |
|
0
|
|
|
Deferred tax liability |
|
0
|
|
|
Current maturities of long-term debt |
|
0
|
|
|
Total current liabilities |
(343,965)
|
(326,957)
|
|
|
Long-term derivative instrument |
0
|
0
|
|
|
Asset retirement obligation—long-term |
0
|
|
|
|
Asset retirement obligation - long-term |
|
0
|
|
|
Long-term debt |
0
|
0
|
|
|
Total liabilities |
(343,965)
|
(326,957)
|
|
|
Stockholders’ equity: |
|
|
|
|
Common stock |
|
0
|
|
|
Paid-in capital |
(266,196)
|
(241,875)
|
|
|
Accumulated other comprehensive (loss) income |
44,903
|
55,177
|
|
|
Retained (deficit) earnings |
169,548
|
145,825
|
|
|
Total stockholders’ equity |
(51,745)
|
(40,873)
|
|
|
Total liabilities and stockholders’ equity |
$ (395,710)
|
$ (367,830)
|
|
|