Guarantor Financial Statements - Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 508,446	$ 112,446	$ 30,205	$ 1,666,574
Accounts receivable	264,317	231,613
Accounts receivable - related party	0	0
Intercompany receivable	0	0
Inventories	14,815	9,108
Other current assets	8,111	5,434
Total current assets	795,689	358,601
Property and equipment:
Oil and natural gas properties, at cost, based on the full cost method of accounting	10,818,378	9,232,694
Midstream assets	355,758	191,519
Other property, equipment and land	85,882	80,776
Accumulated depletion, depreciation, amortization and impairment	(2,545,412)	(2,161,372)
Net property and equipment	8,714,606	7,343,617
Funds held in escrow	62,034	6,304
Investment in subsidiaries	0	0
Deferred tax asset	95,551	0
Investment in real estate, net	106,834	0
Other assets	31,859	62,463
Total assets	9,806,573	7,770,985
Current liabilities:
Accounts payable-trade	85,869	94,590
Intercompany payable	0	0
Other current liabilities	635,918	482,838
Total current liabilities	721,787	577,428
Long-term debt	2,332,359	1,477,347
Derivative instruments	5,931	6,303
Asset retirement obligations	23,897	20,122	19,982
Deferred income taxes	292,795	108,048
Other long-term liabilities	7	0
Total liabilities	3,376,776	2,189,248
Commitments and contingencies
Stockholders’ equity	5,933,359	5,254,860
Non-controlling interest	496,438	326,877
Total equity	6,429,797	5,581,737	5,586,123	4,018,292
Total liabilities and equity	9,806,573	7,770,985
Eliminations [Member]
Current assets:
Cash and cash equivalents	0	0	0	0
Accounts receivable	0	0
Accounts receivable - related party	(7,758)	(5,142)
Intercompany receivable	(3,462,384)	(4,892,118)
Inventories	0	0
Other current assets	0	0
Total current assets	(3,470,142)	(4,897,260)
Property and equipment:
Oil and natural gas properties, at cost, based on the full cost method of accounting	(3,297)	(414)
Midstream assets	0	0
Other property, equipment and land	0	0
Accumulated depletion, depreciation, amortization and impairment	(7,918)	4,342
Net property and equipment	(11,215)	3,928
Funds held in escrow	0	0
Investment in subsidiaries	(4,632,742)	(3,809,557)
Deferred tax asset	0
Investment in real estate, net	0
Other assets	0	0
Total assets	(8,114,099)	(8,702,889)
Current liabilities:
Accounts payable-trade	0	0
Intercompany payable	(3,470,142)	(4,897,260)
Other current liabilities	0	0
Total current liabilities	(3,470,142)	(4,897,260)
Long-term debt	0	0
Derivative instruments	0	0
Asset retirement obligations	0	0
Deferred income taxes	0	0
Other long-term liabilities	0
Total liabilities	(3,470,142)	(4,897,260)
Commitments and contingencies
Stockholders’ equity	(4,444,845)	(4,132,506)
Non-controlling interest	(199,112)	326,877
Total equity	(4,643,957)	(3,805,629)
Total liabilities and equity	(8,114,099)	(8,702,889)
Parent Company [Member] | Reportable Legal Entities [Member]
Current assets:
Cash and cash equivalents	471,148	54,074	20,856	1,643,226
Accounts receivable	0	0
Accounts receivable - related party	0	0
Intercompany receivable	3,199,881	2,624,810
Inventories	0	0
Other current assets	257	618
Total current assets	3,671,286	2,679,502
Property and equipment:
Oil and natural gas properties, at cost, based on the full cost method of accounting	0	0
Midstream assets	0	0
Other property, equipment and land	0	0
Accumulated depletion, depreciation, amortization and impairment	0	0
Net property and equipment	0	0
Funds held in escrow	0	0
Investment in subsidiaries	4,631,753	3,809,557
Deferred tax asset	0
Investment in real estate, net	0
Other assets	0	0
Total assets	8,303,039	6,489,059
Current liabilities:
Accounts payable-trade	0	1
Intercompany payable	0	132,067
Other current liabilities	41,026	7,236
Total current liabilities	41,026	139,304
Long-term debt	2,035,859	986,847
Derivative instruments	0	0
Asset retirement obligations	0	0
Deferred income taxes	292,795	108,048
Other long-term liabilities	0
Total liabilities	2,369,680	1,234,199
Commitments and contingencies
Stockholders’ equity	5,933,359	5,254,860
Non-controlling interest	0	0
Total equity	5,933,359	5,254,860
Total liabilities and equity	8,303,039	6,489,059
Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Current assets:
Cash and cash equivalents	20,469	34,175	4,911	14,135
Accounts receivable	226,299	205,859
Accounts receivable - related party	0	0
Intercompany receivable	262,503	2,267,308
Inventories	14,815	9,108
Other current assets	7,708	4,461
Total current assets	531,794	2,520,911
Property and equipment:
Oil and natural gas properties, at cost, based on the full cost method of accounting	9,209,250	8,129,211
Midstream assets	355,758	191,519
Other property, equipment and land	80,194	80,776
Accumulated depletion, depreciation, amortization and impairment	(2,306,710)	(1,976,248)
Net property and equipment	7,338,492	6,425,258
Funds held in escrow	62,034	0
Investment in subsidiaries	989	0
Deferred tax asset	0
Investment in real estate, net	106,834
Other assets	8,513	25,609
Total assets	8,048,656	8,971,778
Current liabilities:
Accounts payable-trade	85,865	91,629
Intercompany payable	3,470,142	4,765,193
Other current liabilities	590,186	472,933
Total current liabilities	4,146,193	5,329,755
Long-term debt	0	397,000
Derivative instruments	5,931	6,303
Asset retirement obligations	23,897	20,122
Deferred income taxes	0	0
Other long-term liabilities	7
Total liabilities	4,176,028	5,753,180
Commitments and contingencies
Stockholders’ equity	3,872,628	3,218,598
Non-controlling interest	0	0
Total equity	3,872,628	3,218,598
Total liabilities and equity	8,048,656	8,971,778
Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Current assets:
Cash and cash equivalents	16,829	24,197	$ 4,438	$ 9,213
Accounts receivable	38,018	25,754
Accounts receivable - related party	7,758	5,142
Intercompany receivable	0	0
Inventories	0	0
Other current assets	146	355
Total current assets	62,751	55,448
Property and equipment:
Oil and natural gas properties, at cost, based on the full cost method of accounting	1,612,425	1,103,897
Midstream assets	0	0
Other property, equipment and land	5,688	0
Accumulated depletion, depreciation, amortization and impairment	(230,784)	(189,466)
Net property and equipment	1,387,329	914,431
Funds held in escrow	0	6,304
Investment in subsidiaries	0	0
Deferred tax asset	95,551
Investment in real estate, net	0
Other assets	23,346	36,854
Total assets	1,568,977	1,013,037
Current liabilities:
Accounts payable-trade	4	2,960
Intercompany payable	0	0
Other current liabilities	4,706	2,669
Total current liabilities	4,710	5,629
Long-term debt	296,500	93,500
Derivative instruments	0	0
Asset retirement obligations	0	0
Deferred income taxes	0	0
Other long-term liabilities	0
Total liabilities	301,210	99,129
Commitments and contingencies
Stockholders’ equity	572,217	913,908
Non-controlling interest	695,550	0
Total equity	1,267,767	913,908
Total liabilities and equity	$ 1,568,977	$ 1,013,037