Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Sales and revenues:
Sales and revenues	$ 1,076,532	$ 647,880	$ 3,093,978	$ 2,633,848
Operating expenses:
Impairment of unproved properties	221,094	41,000	406,068	83,098
Impairment of gathering systems and facilities	1,157		9,658
Depletion, depreciation, and amortization	243,186	206,968	709,480	610,879
General and administrative expense	59,860	62,203	181,576	191,000
Other operating expenses	183,658	104,136	649,279	324,093
Total operating expenses	1,071,728	719,932	2,975,444	2,080,814
Operating income (loss)	4,804	(72,052)	118,534	553,034
Equity in earnings of unconsolidated affiliates	10,705	7,033	27,832	12,887
Segment assets	15,802,535	14,849,214	15,802,535	14,849,214	$ 15,261,490
Capital expenditures for segment assets	567,221	521,657	1,676,245	1,717,539
Exploration and production
Sales and revenues:
Sales and revenues	982,131	594,244	2,590,409	2,458,524
Gathering and compression
Sales and revenues:
Sales and revenues	4,441	2,609	12,849	7,472
Water handling and treatment
Sales and revenues:
Sales and revenues	404	260	2,450	1,193
Marketing
Sales and revenues:
Sales and revenues	89,556	50,767	488,270	166,659
Operating segments | Exploration and production
Sales and revenues:
Sales and revenues	987,328	597,314	2,606,660	2,469,945
Operating expenses:
Impairment of unproved properties	221,094	41,000	406,068	83,098
Depletion, depreciation, and amortization	204,465	176,188	601,446	521,603
General and administrative expense	45,474	48,289	138,555	148,876
Other operating expenses	30,695	24,259	85,067	75,030
Total operating expenses	979,454	683,334	2,566,489	1,956,120
Operating income (loss)	7,874	(86,020)	40,171	513,825
Segment assets	13,484,457	12,751,606	13,484,457	12,751,606
Capital expenditures for segment assets	485,219	413,742	1,464,041	1,455,168
Operating segments | Gathering and compression
Sales and revenues:
Sales and revenues	133,202	100,518	360,098	290,939
Operating expenses:
Impairment of gathering systems and facilities	1,157		9,658
Depletion, depreciation, and amortization	26,095	22,027	74,215	64,445
General and administrative expense	11,783	9,336	34,140	30,179
Other operating expenses	186	92	204	104
Total operating expenses	51,352	41,923	154,116	123,220
Operating income (loss)	81,850	58,595	205,982	167,719
Equity in earnings of unconsolidated affiliates	10,705	7,033	27,832	12,887
Segment assets	2,367,855	2,158,107	2,367,855	2,158,107
Capital expenditures for segment assets	130,695	99,254	337,448	254,619
Operating segments | Water handling and treatment
Sales and revenues:
Sales and revenues	133,003	93,111	386,674	271,226
Operating expenses:
Depletion, depreciation, and amortization	12,626	8,753	33,819	24,831
General and administrative expense	3,235	4,980	10,827	13,383
Other operating expenses	5,033	3,457	14,925	12,333
Total operating expenses	89,072	68,759	244,839	182,182
Operating income (loss)	43,931	24,352	141,835	89,044
Segment assets	1,043,641	752,982	1,043,641	752,982
Capital expenditures for segment assets	19,258	48,019	77,385	143,470
Operating segments | Marketing
Sales and revenues:
Sales and revenues	89,556	50,767	488,270	166,659
Operating expenses:
Other operating expenses	151,764	78,884	560,924	246,298
Total operating expenses	151,764	78,884	560,924	246,298
Operating income (loss)	(62,208)	(28,117)	(72,654)	(79,639)
Segment assets	20,481	15,807	20,481	15,807
Elimination of intersegment transaction
Sales and revenues:
Sales and revenues	(266,557)	(193,830)	(747,724)	(564,921)
Operating expenses:
General and administrative expense	(632)	(402)	(1,946)	(1,438)
Other operating expenses	(4,020)	(2,556)	(11,841)	(9,672)
Total operating expenses	(199,914)	(152,968)	(550,924)	(427,006)
Operating income (loss)	(66,643)	(40,862)	(196,800)	(137,915)
Segment assets	(1,113,899)	(829,288)	(1,113,899)	(829,288)
Capital expenditures for segment assets	(67,951)	(39,358)	(202,629)	(135,718)
Elimination of intersegment transaction | Exploration and production
Sales and revenues:
Sales and revenues	5,197	3,070	16,251	11,421
Elimination of intersegment transaction | Gathering and compression
Sales and revenues:
Sales and revenues	128,761	97,909	347,249	283,467
Elimination of intersegment transaction | Water handling and treatment
Sales and revenues:
Sales and revenues	132,599	92,851	384,224	270,033
Gathering, compression, water handling and treatment
Operating expenses:
Cost of goods and services sold	326,504	282,134	926,228	815,710
Gathering, compression, water handling and treatment | Operating segments | Exploration and production
Operating expenses:
Cost of goods and services sold	442,602	369,538	1,236,655	1,070,522
Gathering, compression, water handling and treatment | Operating segments | Gathering and compression
Operating expenses:
Cost of goods and services sold	12,131	10,468	35,899	28,492
Gathering, compression, water handling and treatment | Operating segments | Water handling and treatment
Operating expenses:
Cost of goods and services sold	570		570
Gathering, compression, water handling and treatment | Elimination of intersegment transaction
Operating expenses:
Cost of goods and services sold	(128,799)	(97,872)	(346,896)	(283,304)
Oil and Gas, Operation and Maintenance
Operating expenses:
Cost of goods and services sold	36,269	23,491	93,155	56,034
Oil and Gas, Operation and Maintenance | Operating segments | Exploration and production
Operating expenses:
Cost of goods and services sold	35,124	24,060	98,698	56,991
Oil and Gas, Operation and Maintenance | Operating segments | Water handling and treatment
Operating expenses:
Cost of goods and services sold	67,608	51,569	184,698	131,635
Oil and Gas, Operation and Maintenance | Elimination of intersegment transaction
Operating expenses:
Cost of goods and services sold	$ (66,463)	$ (52,138)	$ (190,241)	$ (132,592)