Condensed Consolidating Financial Information - Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Thousands |
Sep. 30, 2015 |
Dec. 31, 2014 |
Sep. 30, 2014 |
Dec. 31, 2013 |
Current assets: |
|
|
|
|
Cash and cash equivalents |
$ 228,111
|
$ 142,340
|
$ 152,883
|
$ 458,956
|
Accounts receivable—oil and gas |
66,271
|
103,858
|
|
|
Accounts receivable - related parties |
149
|
46
|
|
|
Accounts receivable - intercompany |
|
0
|
|
|
Prepaid expenses and other current assets |
16,156
|
3,714
|
|
|
Short-term derivative instruments |
116,100
|
78,391
|
|
|
Total current assets |
426,787
|
328,349
|
|
|
Property and equipment: |
|
|
|
|
Oil and natural gas properties |
5,258,762
|
3,923,154
|
|
|
Other property and equipment |
27,670
|
18,344
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
(1,896,413)
|
(1,050,879)
|
|
|
Property and equipment, net |
3,390,019
|
2,890,619
|
|
|
Other assets: |
|
|
|
|
Equity investments and investments in subsidiaries |
295,103
|
369,581
|
|
|
Derivative instruments |
51,171
|
24,448
|
|
|
Deferred tax asset |
27,368
|
0
|
|
|
Other assets |
24,982
|
19,396
|
|
|
Total other assets |
398,624
|
413,425
|
|
|
Total assets |
4,215,430
|
3,632,393
|
|
|
Current liabilities: |
|
|
|
|
Accounts payable and accrued liabilities |
312,116
|
371,410
|
|
|
Accounts payable - intercompany |
0
|
0
|
|
|
Asset retirement obligation—current |
75
|
75
|
75
|
|
Deferred tax liability - current |
38,734
|
27,070
|
|
|
Short-term derivative instruments |
2,351
|
|
|
|
Current maturities of long-term debt |
1,695
|
168
|
|
|
Total current liabilities |
354,971
|
398,723
|
|
|
Long-term derivative instrument |
3,208
|
0
|
|
|
Asset retirement obligation—long-term |
23,073
|
17,863
|
16,318
|
|
Deferred tax liability |
0
|
203,195
|
|
|
Long-term debt, net of current maturities |
963,048
|
716,316
|
|
|
Total liabilities |
1,344,300
|
1,336,097
|
|
|
Stockholders’ equity: |
|
|
|
|
Common stock |
1,082
|
856
|
|
|
Paid-in capital |
2,820,500
|
1,828,602
|
|
|
Accumulated other comprehensive (loss) income |
(49,950)
|
(26,675)
|
|
|
Retained earnings (accumulated deficit) |
99,498
|
493,513
|
|
|
Total stockholders’ equity |
2,871,130
|
2,296,296
|
2,189,470
|
2,050,238
|
Total liabilities and stockholders’ equity |
4,215,430
|
3,632,393
|
|
|
Parent [Member] |
|
|
|
|
Current assets: |
|
|
|
|
Cash and cash equivalents |
226,161
|
141,535
|
152,479
|
451,431
|
Accounts receivable—oil and gas |
66,228
|
103,762
|
|
|
Accounts receivable - related parties |
149
|
46
|
|
|
Accounts receivable - intercompany |
334,886
|
45,222
|
|
|
Prepaid expenses and other current assets |
16,156
|
3,714
|
|
|
Short-term derivative instruments |
116,100
|
78,391
|
|
|
Total current assets |
759,680
|
372,670
|
|
|
Property and equipment: |
|
|
|
|
Oil and natural gas properties |
4,934,813
|
3,887,874
|
|
|
Other property and equipment |
27,627
|
18,301
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
(1,896,385)
|
(1,050,855)
|
|
|
Property and equipment, net |
3,066,055
|
2,855,320
|
|
|
Other assets: |
|
|
|
|
Equity investments and investments in subsidiaries |
285,980
|
360,238
|
|
|
Derivative instruments |
51,171
|
24,448
|
|
|
Deferred tax asset |
27,368
|
|
|
|
Other assets |
24,982
|
19,396
|
|
|
Total other assets |
389,501
|
404,082
|
|
|
Total assets |
4,215,236
|
3,632,072
|
|
|
Current liabilities: |
|
|
|
|
Accounts payable and accrued liabilities |
311,922
|
371,089
|
|
|
Accounts payable - intercompany |
0
|
0
|
|
|
Asset retirement obligation—current |
75
|
75
|
|
|
Deferred tax liability - current |
38,734
|
27,070
|
|
|
Short-term derivative instruments |
2,351
|
|
|
|
Current maturities of long-term debt |
1,695
|
168
|
|
|
Total current liabilities |
354,777
|
398,402
|
|
|
Long-term derivative instrument |
3,208
|
|
|
|
Asset retirement obligation—long-term |
23,073
|
17,863
|
|
|
Deferred tax liability |
|
203,195
|
|
|
Long-term debt, net of current maturities |
963,048
|
716,316
|
|
|
Total liabilities |
1,344,106
|
1,335,776
|
|
|
Stockholders’ equity: |
|
|
|
|
Common stock |
1,082
|
856
|
|
|
Paid-in capital |
2,820,500
|
1,828,602
|
|
|
Accumulated other comprehensive (loss) income |
(49,950)
|
(26,675)
|
|
|
Retained earnings (accumulated deficit) |
99,498
|
493,513
|
|
|
Total stockholders’ equity |
2,871,130
|
2,296,296
|
|
|
Total liabilities and stockholders’ equity |
4,215,236
|
3,632,072
|
|
|
Guarantors [Member] |
|
|
|
|
Current assets: |
|
|
|
|
Cash and cash equivalents |
1,949
|
804
|
404
|
7,525
|
Accounts receivable—oil and gas |
43
|
96
|
|
|
Accounts receivable - related parties |
0
|
0
|
|
|
Accounts receivable - intercompany |
55
|
27
|
|
|
Prepaid expenses and other current assets |
|
0
|
|
|
Short-term derivative instruments |
0
|
0
|
|
|
Total current assets |
2,047
|
927
|
|
|
Property and equipment: |
|
|
|
|
Oil and natural gas properties |
324,678
|
35,990
|
|
|
Other property and equipment |
43
|
43
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
(28)
|
(24)
|
|
|
Property and equipment, net |
324,693
|
36,009
|
|
|
Other assets: |
|
|
|
|
Equity investments and investments in subsidiaries |
|
0
|
|
|
Derivative instruments |
0
|
0
|
|
|
Deferred tax asset |
0
|
|
|
|
Other assets |
|
0
|
|
|
Total assets |
326,740
|
36,936
|
|
|
Current liabilities: |
|
|
|
|
Accounts payable and accrued liabilities |
194
|
321
|
|
|
Accounts payable - intercompany |
334,817
|
45,143
|
|
|
Asset retirement obligation—current |
|
0
|
|
|
Deferred tax liability - current |
|
0
|
|
|
Current maturities of long-term debt |
|
0
|
|
|
Total current liabilities |
335,011
|
45,464
|
|
|
Long-term derivative instrument |
0
|
|
|
|
Asset retirement obligation—long-term |
0
|
0
|
|
|
Deferred tax liability |
|
0
|
|
|
Long-term debt, net of current maturities |
0
|
0
|
|
|
Total liabilities |
335,011
|
45,464
|
|
|
Stockholders’ equity: |
|
|
|
|
Common stock |
|
0
|
|
|
Paid-in capital |
322
|
322
|
|
|
Accumulated other comprehensive (loss) income |
|
0
|
|
|
Retained earnings (accumulated deficit) |
(8,593)
|
(8,850)
|
|
|
Total stockholders’ equity |
(8,271)
|
(8,528)
|
|
|
Total liabilities and stockholders’ equity |
326,740
|
36,936
|
|
|
Non-Guarantor [Member] |
|
|
|
|
Current assets: |
|
|
|
|
Cash and cash equivalents |
1
|
1
|
0
|
0
|
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
|
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 and investments in subsidiaries |
99,489
|
180,217
|
|
|
Derivative instruments |
0
|
0
|
|
|
Deferred tax asset |
0
|
|
|
|
Other assets |
|
0
|
|
|
Total other assets |
99,489
|
180,217
|
|
|
Total assets |
99,490
|
180,218
|
|
|
Current liabilities: |
|
|
|
|
Accounts payable and accrued liabilities |
|
0
|
|
|
Accounts payable - intercompany |
124
|
106
|
|
|
Asset retirement obligation—current |
|
0
|
|
|
Deferred tax liability - current |
|
0
|
|
|
Current maturities of long-term debt |
|
0
|
|
|
Total current liabilities |
124
|
106
|
|
|
Long-term derivative instrument |
0
|
|
|
|
Asset retirement obligation—long-term |
0
|
0
|
|
|
Deferred tax liability |
|
0
|
|
|
Long-term debt, net of current maturities |
0
|
0
|
|
|
Total liabilities |
124
|
106
|
|
|
Stockholders’ equity: |
|
|
|
|
Common stock |
|
0
|
|
|
Paid-in capital |
240,916
|
227,079
|
|
|
Accumulated other comprehensive (loss) income |
(49,950)
|
(26,675)
|
|
|
Retained earnings (accumulated deficit) |
(91,600)
|
(20,292)
|
|
|
Total stockholders’ equity |
99,366
|
180,112
|
|
|
Total liabilities and stockholders’ equity |
99,490
|
180,218
|
|
|
Eliminations [Member] |
|
|
|
|
Current assets: |
|
|
|
|
Cash and cash equivalents |
0
|
0
|
$ 0
|
$ 0
|
Accounts receivable—oil and gas |
|
0
|
|
|
Accounts receivable - related parties |
0
|
0
|
|
|
Accounts receivable - intercompany |
(334,941)
|
(45,249)
|
|
|
Prepaid expenses and other current assets |
|
0
|
|
|
Short-term derivative instruments |
0
|
0
|
|
|
Total current assets |
(334,941)
|
(45,249)
|
|
|
Property and equipment: |
|
|
|
|
Oil and natural gas properties |
(729)
|
(710)
|
|
|
Other property and equipment |
|
0
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
|
0
|
|
|
Property and equipment, net |
(729)
|
(710)
|
|
|
Other assets: |
|
|
|
|
Equity investments and investments in subsidiaries |
(90,366)
|
(170,874)
|
|
|
Derivative instruments |
0
|
0
|
|
|
Deferred tax asset |
0
|
|
|
|
Other assets |
|
0
|
|
|
Total other assets |
(90,366)
|
(170,874)
|
|
|
Total assets |
(426,036)
|
(216,833)
|
|
|
Current liabilities: |
|
|
|
|
Accounts payable and accrued liabilities |
|
0
|
|
|
Accounts payable - intercompany |
(334,941)
|
(45,249)
|
|
|
Asset retirement obligation—current |
|
0
|
|
|
Deferred tax liability - current |
|
0
|
|
|
Current maturities of long-term debt |
|
0
|
|
|
Total current liabilities |
(334,941)
|
(45,249)
|
|
|
Long-term derivative instrument |
0
|
|
|
|
Asset retirement obligation—long-term |
0
|
0
|
|
|
Deferred tax liability |
|
0
|
|
|
Long-term debt, net of current maturities |
0
|
0
|
|
|
Total liabilities |
(334,941)
|
(45,249)
|
|
|
Stockholders’ equity: |
|
|
|
|
Common stock |
|
0
|
|
|
Paid-in capital |
(241,238)
|
(227,401)
|
|
|
Accumulated other comprehensive (loss) income |
49,950
|
26,675
|
|
|
Retained earnings (accumulated deficit) |
100,193
|
29,142
|
|
|
Total stockholders’ equity |
(91,095)
|
(171,584)
|
|
|
Total liabilities and stockholders’ equity |
$ (426,036)
|
$ (216,833)
|
|
|