Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Sales and revenues:
Sales and revenues	$ 1,116,503	$ 1,443,335	$ 1,588,309	$ 3,049,736
Operating expenses:
Lease operating	13,854	10,786	37,190	25,561
Gathering, compression, processing, and transportation	234,915	160,302	649,713	490,633
Depletion, depreciation, and amortization	199,113	188,667	588,057	548,013
General and administrative expense	57,577	59,685	173,966	177,925
Total operating expenses	649,171	502,220	1,932,101	1,572,676
Operating income (loss)	467,332	941,115	(343,792)	1,477,060
Segment assets	14,629,253		14,629,253		$ 14,115,493
Exploration and production
Sales and revenues:
Sales and revenues	1,020,448	1,403,673	1,302,722	2,892,435
Gathering and compression
Sales and revenues:
Sales and revenues	78,064	59,258	219,607	168,094
Fresh Water Distribution
Sales and revenues:
Sales and revenues	72,411	22,446	203,750	87,537
Marketing
Sales and revenues:
Sales and revenues	97,076	35,633	287,194	143,242
Operating segments
Sales and revenues:
Sales and revenues	1,116,503	1,443,335	1,588,309	3,049,736
Operating expenses:
Lease operating	13,854	10,786	37,190	25,561
Gathering, compression, processing, and transportation	234,915	160,302	649,713	490,633
Depletion, depreciation, and amortization	199,113	188,667	588,057	548,013
General and administrative expense	57,577	59,685	173,966	177,925
Other operating expenses	143,712	82,780	483,175	330,544
Total operating expenses	649,171	502,220	1,932,101	1,572,676
Operating income (loss)	467,332	941,115	(343,792)	1,477,060
Segment assets	14,629,253	13,577,074	14,629,253	13,577,074
Capital expenditures for segment assets	982,060	510,035	1,927,450	1,888,054
Operating segments | Exploration and production
Sales and revenues:
Sales and revenues	1,016,458	1,403,275	1,291,008	2,891,410
Operating expenses:
Lease operating	13,710	10,721	37,299	24,981
Gathering, compression, processing, and transportation	303,753	211,469	838,936	630,708
Depletion, depreciation, and amortization	172,735	166,900	513,302	483,991
General and administrative expense	44,637	46,165	135,356	140,821
Other operating expenses	31,266	28,044	104,279	113,881
Total operating expenses	566,101	463,299	1,629,172	1,394,382
Operating income (loss)	454,347	940,374	(326,450)	1,498,053
Segment assets	12,966,493	11,940,524	12,966,493	11,940,524
Capital expenditures for segment assets	909,837	399,695	1,734,914	1,590,904
Operating segments | Gathering and compression
Sales and revenues:
Sales and revenues	2,745	3,468	9,463	8,433
Operating expenses:
Gathering, compression, processing, and transportation	6,400	4,699	20,567	19,792
Depletion, depreciation, and amortization	18,540	15,282	52,780	45,255
General and administrative expense	10,282	11,265	29,755	30,685
Other operating expenses	(1,708)	(7,863)	(809)	25
Total operating expenses	33,514	23,383	102,293	95,757
Operating income (loss)	44,550	35,875	117,314	72,337
Segment assets	1,669,667	1,410,920	1,669,667	1,410,920
Capital expenditures for segment assets	56,836	82,768	154,136	282,813
Operating segments | Fresh Water Distribution
Sales and revenues:
Sales and revenues	224	959	644	6,651
Operating expenses:
Lease operating	28,978	3,973	104,009	16,576
Depletion, depreciation, and amortization	7,838	6,485	21,975	18,767
General and administrative expense	3,033	2,577	9,957	7,238
Other operating expenses	3,070	800	11,568	2,437
Total operating expenses	42,919	13,835	147,509	45,018
Operating income (loss)	29,492	8,611	56,241	42,519
Segment assets	562,995	487,734	562,995	487,734
Capital expenditures for segment assets	58,730	45,151	137,355	79,227
Operating segments | Marketing
Sales and revenues:
Sales and revenues	97,076	35,633	287,194	143,242
Operating expenses:
Other operating expenses	114,611	61,799	378,521	214,201
Total operating expenses	114,611	61,799	378,521	214,201
Operating income (loss)	(17,535)	(26,166)	(91,327)	(70,959)
Segment assets	33,114	5,847	33,114	5,847
Elimination of intersegment transaction
Sales and revenues:
Sales and revenues	(151,496)	(77,675)	(424,964)	(241,572)
Operating expenses:
Lease operating	(28,834)	(3,908)	(104,118)	(15,996)
Gathering, compression, processing, and transportation	(75,238)	(55,866)	(209,790)	(159,867)
General and administrative expense	(375)	(322)	(1,102)	(819)
Other operating expenses	(3,527)		(10,384)
Total operating expenses	(107,974)	(60,096)	(325,394)	(176,682)
Operating income (loss)	(43,522)	(17,579)	(99,570)	(64,890)
Segment assets	(603,016)	(267,951)	(603,016)	(267,951)
Capital expenditures for segment assets	(43,343)	(17,579)	(98,955)	(64,890)
Elimination of intersegment transaction | Exploration and production
Sales and revenues:
Sales and revenues	3,990	398	11,714	1,025
Elimination of intersegment transaction | Gathering and compression
Sales and revenues:
Sales and revenues	75,319	55,790	210,144	159,661
Elimination of intersegment transaction | Fresh Water Distribution
Sales and revenues:
Sales and revenues	$ 72,187	$ 21,487	$ 203,106	$ 80,886