Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Sales and revenues:
Sales and revenues	$ 647,880	$ 1,116,503	$ 2,633,848	$ 1,588,309
Operating expenses:
Lease operating	23,491	13,854	56,034	37,190
Gathering, compression, processing, and transportation	282,134	234,915	815,710	649,713
Depletion, depreciation, and amortization	206,968	199,113	610,879	588,057
General and administrative expense	62,203	57,577	191,000	173,966
Other operating expenses			407,191	483,175
Total operating expenses	719,932	649,171	2,080,814	1,932,101
Operating income (loss)	(72,052)	467,332	553,034	(343,792)
Equity in earnings of unconsolidated affiliate	7,033	1,543	12,887	2,027
Segment assets	14,849,214	14,629,253	14,849,214	14,629,253	$ 14,255,550
Capital expenditures for segment assets			1,717,539	1,927,450
Exploration and production
Sales and revenues:
Sales and revenues	594,244	1,016,458	2,458,524	1,291,008
Gathering and compression
Sales and revenues:
Sales and revenues	2,609	2,745	7,472	9,463
Fresh Water Distribution
Sales and revenues:
Sales and revenues	260	224	1,193	644
Marketing
Sales and revenues:
Sales and revenues	50,767	97,076	166,659	287,194
Operating segments
Sales and revenues:
Sales and revenues	647,880	1,116,503
Operating expenses:
Lease operating	23,491	13,854
Gathering, compression, processing, and transportation	282,134	234,915
Depletion, depreciation, and amortization	206,968	199,113
General and administrative expense	62,203	57,577
Other operating expenses	145,136	143,712
Total operating expenses	719,932	649,171
Operating income (loss)	(72,052)	467,332
Equity in earnings of unconsolidated affiliate	7,033	1,543	12,887	2,027
Segment assets	14,849,214	14,629,253	14,849,214	14,629,253
Capital expenditures for segment assets	521,657	982,060
Operating segments | Exploration and production
Sales and revenues:
Sales and revenues	597,314	1,020,448	2,469,945	1,302,722
Operating expenses:
Lease operating	24,060	13,710	56,991	37,299
Gathering, compression, processing, and transportation	369,538	303,753	1,070,522	838,936
Depletion, depreciation, and amortization	176,188	172,735	521,603	513,302
General and administrative expense	48,289	44,637	148,876	135,356
Other operating expenses	65,259	31,266	158,128	104,279
Total operating expenses	683,334	566,101	1,956,120	1,629,172
Operating income (loss)	(86,020)	454,347	513,825	(326,450)
Segment assets	12,751,606	12,966,493	12,751,606	12,966,493
Capital expenditures for segment assets	415,088	909,837	1,456,870	1,734,914
Operating segments | Gathering and compression
Sales and revenues:
Sales and revenues	100,518	78,064	290,939	219,607
Operating expenses:
Gathering, compression, processing, and transportation	10,468	6,400	28,492	20,567
Depletion, depreciation, and amortization	22,027	18,540	64,445	52,780
General and administrative expense	9,336	10,282	30,179	29,755
Other operating expenses	92	(1,708)	104	(809)
Total operating expenses	41,923	33,514	123,220	102,293
Operating income (loss)	58,595	44,550	167,719	117,314
Equity in earnings of unconsolidated affiliate	7,033	1,543	12,887	2,027
Segment assets	2,158,107	1,669,667	2,158,107	1,669,667
Capital expenditures for segment assets	99,254	56,836	254,619	154,136
Operating segments | Fresh Water Distribution
Sales and revenues:
Sales and revenues	93,111	72,411	271,226	203,750
Operating expenses:
Lease operating	51,569	28,978	131,635	104,009
Depletion, depreciation, and amortization	8,753	7,838	24,831	21,975
General and administrative expense	4,980	3,033	13,383	9,957
Other operating expenses	3,457	3,070	12,333	11,568
Total operating expenses	68,759	42,919	182,182	147,509
Operating income (loss)	24,352	29,492	89,044	56,241
Segment assets	752,982	562,995	752,982	562,995
Capital expenditures for segment assets	48,019	58,730	143,470	137,355
Operating segments | Marketing
Sales and revenues:
Sales and revenues	50,767	97,076		287,194
Operating expenses:
Other operating expenses	78,884	114,611	246,298	378,521
Total operating expenses	78,884	114,611	246,298	378,521
Operating income (loss)	(28,117)	(17,535)	(79,639)	(91,327)
Segment assets	15,807	33,114	15,807	33,114
Elimination of intersegment transaction
Sales and revenues:
Sales and revenues	(193,830)	(151,496)	(564,921)	(424,964)
Operating expenses:
Lease operating	(52,138)	(28,834)	(132,592)	(104,118)
Gathering, compression, processing, and transportation	(97,872)	(75,238)	(283,304)	(209,790)
General and administrative expense	(402)	(375)	(1,438)	(1,102)
Other operating expenses	(2,556)	(3,527)	(9,672)	(10,384)
Total operating expenses	(152,968)	(107,974)	(427,006)	(325,394)
Operating income (loss)	(40,862)	(43,522)	(137,915)	(99,570)
Segment assets	(829,288)	(603,016)	(829,288)	(603,016)
Capital expenditures for segment assets	(40,704)	(43,343)	(137,420)	(98,955)
Elimination of intersegment transaction | Exploration and production
Sales and revenues:
Sales and revenues	3,070	3,990	11,421	11,714
Elimination of intersegment transaction | Gathering and compression
Sales and revenues:
Sales and revenues	97,909	75,319	283,467	210,144
Elimination of intersegment transaction | Fresh Water Distribution
Sales and revenues:
Sales and revenues	$ 92,851	$ 72,187	270,033	$ 203,106
Elimination of intersegment transaction | Marketing
Sales and revenues:
Sales and revenues			$ 166,659