Condensed Consolidating Financial Information - Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Thousands |
Jun. 30, 2015 |
Dec. 31, 2014 |
Jun. 30, 2014 |
Dec. 31, 2013 |
Current assets: |
|
|
|
|
Cash and cash equivalents |
$ 525,488
|
$ 142,340
|
$ 75,293
|
$ 458,956
|
Restricted cash |
75,005
|
0
|
|
|
Accounts receivable—oil and gas |
86,621
|
103,858
|
|
|
Accounts receivable - related parties |
90
|
46
|
|
|
Accounts receivable - intercompany |
|
0
|
|
|
Prepaid expenses and other current assets |
15,168
|
3,714
|
|
|
Short-term derivative instruments |
77,350
|
78,391
|
|
|
Total current assets |
779,722
|
328,349
|
|
|
Property and equipment: |
|
|
|
|
Oil and natural gas properties |
4,798,835
|
3,923,154
|
|
|
Other property and equipment |
22,930
|
18,344
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
(1,211,308)
|
(1,050,879)
|
|
|
Property and equipment, net |
3,610,457
|
2,890,619
|
|
|
Other assets: |
|
|
|
|
Equity investments and investments in subsidiaries |
362,391
|
369,581
|
|
|
Derivative instruments |
25,871
|
24,448
|
|
|
Other assets |
25,418
|
19,396
|
|
|
Total other assets |
413,680
|
413,425
|
|
|
Total assets |
4,803,859
|
3,632,393
|
|
|
Current liabilities: |
|
|
|
|
Accounts payable and accrued liabilities |
318,725
|
371,410
|
|
|
Accounts payable - intercompany |
0
|
0
|
|
|
Asset retirement obligation—current |
75
|
75
|
795
|
|
Short-term derivative instruments |
937
|
|
|
|
Deferred tax liability - current |
26,508
|
27,070
|
|
|
Current maturities of long-term debt |
1,738
|
168
|
|
|
Total current liabilities |
347,983
|
398,723
|
|
|
Long-term derivative instrument |
2,753
|
0
|
|
|
Asset retirement obligation—long-term |
21,202
|
17,863
|
15,181
|
|
Deferred tax liability |
201,022
|
203,195
|
|
|
Long-term debt, net of current maturities |
963,593
|
716,316
|
|
|
Total liabilities |
1,536,553
|
1,336,097
|
|
|
Stockholders’ equity: |
|
|
|
|
Common stock |
1,081
|
856
|
|
|
Paid-in capital |
2,816,930
|
1,828,602
|
|
|
Accumulated other comprehensive income (loss) |
(38,412)
|
(26,675)
|
|
|
Retained earnings (accumulated deficit) |
487,707
|
493,513
|
|
|
Total stockholders’ equity |
3,267,306
|
2,296,296
|
2,188,499
|
2,050,238
|
Total liabilities and stockholders’ equity |
4,803,859
|
3,632,393
|
|
|
Parent [Member] |
|
|
|
|
Current assets: |
|
|
|
|
Cash and cash equivalents |
524,240
|
141,535
|
72,921
|
451,431
|
Restricted cash |
75,005
|
|
|
|
Accounts receivable—oil and gas |
86,558
|
103,762
|
|
|
Accounts receivable - related parties |
90
|
46
|
|
|
Accounts receivable - intercompany |
48,401
|
45,222
|
|
|
Prepaid expenses and other current assets |
15,168
|
3,714
|
|
|
Short-term derivative instruments |
77,350
|
78,391
|
|
|
Total current assets |
826,812
|
372,670
|
|
|
Property and equipment: |
|
|
|
|
Oil and natural gas properties |
4,760,793
|
3,887,874
|
|
|
Other property and equipment |
22,887
|
18,301
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
(1,211,281)
|
(1,050,855)
|
|
|
Property and equipment, net |
3,572,399
|
2,855,320
|
|
|
Other assets: |
|
|
|
|
Equity investments and investments in subsidiaries |
353,243
|
360,238
|
|
|
Derivative instruments |
25,871
|
24,448
|
|
|
Other assets |
25,418
|
19,396
|
|
|
Total other assets |
404,532
|
404,082
|
|
|
Total assets |
4,803,743
|
3,632,072
|
|
|
Current liabilities: |
|
|
|
|
Accounts payable and accrued liabilities |
318,609
|
371,089
|
|
|
Accounts payable - intercompany |
0
|
0
|
|
|
Asset retirement obligation—current |
75
|
75
|
|
|
Short-term derivative instruments |
937
|
|
|
|
Deferred tax liability - current |
26,508
|
27,070
|
|
|
Current maturities of long-term debt |
1,738
|
168
|
|
|
Total current liabilities |
347,867
|
398,402
|
|
|
Long-term derivative instrument |
2,753
|
|
|
|
Asset retirement obligation—long-term |
21,202
|
17,863
|
|
|
Deferred tax liability |
201,022
|
203,195
|
|
|
Long-term debt, net of current maturities |
963,593
|
716,316
|
|
|
Total liabilities |
1,536,437
|
1,335,776
|
|
|
Stockholders’ equity: |
|
|
|
|
Common stock |
1,081
|
856
|
|
|
Paid-in capital |
2,816,930
|
1,828,602
|
|
|
Accumulated other comprehensive income (loss) |
(38,412)
|
(26,675)
|
|
|
Retained earnings (accumulated deficit) |
487,707
|
493,513
|
|
|
Total stockholders’ equity |
3,267,306
|
2,296,296
|
|
|
Total liabilities and stockholders’ equity |
4,803,743
|
3,632,072
|
|
|
Guarantors [Member] |
|
|
|
|
Current assets: |
|
|
|
|
Cash and cash equivalents |
1,247
|
804
|
2,371
|
7,525
|
Accounts receivable—oil and gas |
63
|
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 |
1,365
|
927
|
|
|
Property and equipment: |
|
|
|
|
Oil and natural gas properties |
38,771
|
35,990
|
|
|
Other property and equipment |
43
|
43
|
|
|
Accumulated depletion, depreciation, amortization and impairment |
(27)
|
(24)
|
|
|
Property and equipment, net |
38,787
|
36,009
|
|
|
Other assets: |
|
|
|
|
Equity investments and investments in subsidiaries |
|
0
|
|
|
Derivative instruments |
0
|
0
|
|
|
Other assets |
|
0
|
|
|
Total assets |
40,152
|
36,936
|
|
|
Current liabilities: |
|
|
|
|
Accounts payable and accrued liabilities |
116
|
321
|
|
|
Accounts payable - intercompany |
48,326
|
45,143
|
|
|
Asset retirement obligation—current |
|
0
|
|
|
Deferred tax liability - current |
|
0
|
|
|
Current maturities of long-term debt |
|
0
|
|
|
Total current liabilities |
48,442
|
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 |
48,442
|
45,464
|
|
|
Stockholders’ equity: |
|
|
|
|
Common stock |
|
0
|
|
|
Paid-in capital |
322
|
322
|
|
|
Accumulated other comprehensive income (loss) |
|
0
|
|
|
Retained earnings (accumulated deficit) |
(8,612)
|
(8,850)
|
|
|
Total stockholders’ equity |
(8,290)
|
(8,528)
|
|
|
Total liabilities and stockholders’ equity |
40,152
|
36,936
|
|
|
Non-Guarantor [Member] |
|
|
|
|
Current assets: |
|
|
|
|
Cash and cash equivalents |
1
|
1
|
1
|
0
|
Restricted cash |
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 |
164,112
|
180,217
|
|
|
Derivative instruments |
0
|
0
|
|
|
Other assets |
|
0
|
|
|
Total other assets |
164,112
|
180,217
|
|
|
Total assets |
164,113
|
180,218
|
|
|
Current liabilities: |
|
|
|
|
Accounts payable and accrued liabilities |
|
0
|
|
|
Accounts payable - intercompany |
130
|
106
|
|
|
Asset retirement obligation—current |
|
0
|
|
|
Deferred tax liability - current |
|
0
|
|
|
Current maturities of long-term debt |
|
0
|
|
|
Total current liabilities |
130
|
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 |
130
|
106
|
|
|
Stockholders’ equity: |
|
|
|
|
Common stock |
|
0
|
|
|
Paid-in capital |
235,347
|
227,079
|
|
|
Accumulated other comprehensive income (loss) |
(38,412)
|
(26,675)
|
|
|
Retained earnings (accumulated deficit) |
(32,952)
|
(20,292)
|
|
|
Total stockholders’ equity |
163,983
|
180,112
|
|
|
Total liabilities and stockholders’ equity |
164,113
|
180,218
|
|
|
Eliminations [Member] |
|
|
|
|
Current assets: |
|
|
|
|
Cash and cash equivalents |
0
|
0
|
$ 0
|
$ 0
|
Restricted cash |
0
|
|
|
|
Accounts receivable—oil and gas |
|
0
|
|
|
Accounts receivable - related parties |
0
|
0
|
|
|
Accounts receivable - intercompany |
(48,456)
|
(45,249)
|
|
|
Prepaid expenses and other current assets |
|
0
|
|
|
Short-term derivative instruments |
0
|
0
|
|
|
Total current assets |
(48,456)
|
(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 |
(154,964)
|
(170,874)
|
|
|
Derivative instruments |
0
|
0
|
|
|
Other assets |
|
0
|
|
|
Total other assets |
(154,964)
|
(170,874)
|
|
|
Total assets |
(204,149)
|
(216,833)
|
|
|
Current liabilities: |
|
|
|
|
Accounts payable and accrued liabilities |
|
0
|
|
|
Accounts payable - intercompany |
(48,456)
|
(45,249)
|
|
|
Asset retirement obligation—current |
|
0
|
|
|
Deferred tax liability - current |
|
0
|
|
|
Current maturities of long-term debt |
|
0
|
|
|
Total current liabilities |
(48,456)
|
(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 |
(48,456)
|
(45,249)
|
|
|
Stockholders’ equity: |
|
|
|
|
Common stock |
|
0
|
|
|
Paid-in capital |
(235,669)
|
(227,401)
|
|
|
Accumulated other comprehensive income (loss) |
38,412
|
26,675
|
|
|
Retained earnings (accumulated deficit) |
41,564
|
29,142
|
|
|
Total stockholders’ equity |
(155,693)
|
(171,584)
|
|
|
Total liabilities and stockholders’ equity |
$ (204,149)
|
$ (216,833)
|
|
|