Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues and Other Operating Income:
Gain on Commodity Derivative Instruments	$ 18,005	$ 19,183	$ 78,752	$ 80,508
Other Operating Income	3,903	20,176	23,146	52,483
Total Revenue	397,126	287,185	1,294,979	978,180
Operating Expense
Lease Operating Expense	16,202	21,755	78,350	64,459
Production, Ad Valorem, and Other Fees	7,342	5,919	24,277	19,854
Depreciation, Depletion and Amortization	119,585	102,012	363,338	289,329
Purchased Gas Costs	10,602	13,142	37,404	32,231
Impairment of Exploration and Production Properties	0	0	0	137,865
Impairment of Other Intangible Assets	0	0	18,650	0
Selling, General, and Administrative Costs	32,435	21,469	98,693	65,025
Other Operating Expense	17,405	27,544	51,238	69,825
Total Operating Expense	275,799	295,089	912,286	992,268
Other (Income) Expense
Other Expense (Income)	1,105	8,250	(4,812)	17,803
Gain on Asset Sales	(134,320)	(45,743)	(148,942)	(184,319)
Gain on Previously Held Equity Interest	0	0	(623,663)	0
Loss on Debt Extinguishment	15,385	2,019	54,433	1,233
Interest Expense	35,723	38,836	112,712	121,124
Total Other (Income) Expense	(82,107)	3,362	(610,272)	(44,159)
Total Expense	193,692	298,451	302,014	948,109
Earnings (Loss) from Continuing Operations Before Income Tax	203,434	(11,266)	992,965	30,071
Income Tax Expense	56,678	10,530	239,269	21,066
Income (Loss) from Continuing Operations	146,756	(21,796)	753,696	9,005
(Loss) Income from Discontinued Operations, net	0	(4,645)	0	95,099
Net Income (Loss)	146,756	(26,441)	753,696	104,104
Less: Net Income Attributable to Noncontrolling Interest	21,727	0	59,090	0
Net Income	125,029	(26,441)	694,606	104,104
Natural Gas, NGLs and Oil Revenue [Member]
Revenues and Other Operating Income:
Revenue from Contracts with Customers	344,712	234,442	1,084,851	812,511
Purchased Gas Revenue [Member]
Revenues and Other Operating Income:
Revenue from Contracts with Customers	10,560	13,384	38,546	32,678
Midstream Revenue [Member]
Revenues and Other Operating Income:
Revenue from Contracts with Customers	19,946	0	69,684	0
Natural Gas, Gathering, Transportation, Marketing and Processing [Member]
Operating Expense
Cost of Goods Sold	68,907	98,769	230,935	279,699
Oil and Gas, Exploration and Production [Member]
Operating Expense
Cost of Goods Sold	$ 3,321	$ 4,479	$ 9,401	$ 33,981