Properties and Equipment Properties and Equipment (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) Wells	Dec. 31, 2018 USD ($) Wells	Dec. 31, 2017 USD ($)
Property, Plant and Equipment [Line Items]
Exploratory Wells Drilled, Net Nonproductive	$ 0	$ 113	$ 41,297
Capitalized Exploratory Well Costs	16,078	12,188	15,448
Reclassification to Well, Facilities, and Equipment Based on Determination of Proved Reserves	31,901	35,127
Properties and equipment, net	4,095,202	4,002,862
Assets	4,448,680	4,544,145
Asset retirement obligations	95,051	85,312
Liabilities	2,113,173	2,017,437
Proved Natural Gas and Crude Oil Properties	6,241,780	5,452,613
Unproved Natural Gas and Crude Oil Properties	403,379	492,594
Total Natural Gas and Crude Oil Properties	6,645,159	5,945,207
Transportation and Other Equipment	41,888	60,612
Land and Buildings	12,312	11,243
Construction in Progress	408,428	356,095
Property and Equipment, at cost	7,107,787	6,373,157
Accumulated Depreciation, Depletion and Amortization	(3,012,585)	(2,370,295)
Capitalized Exploratory Well Cost, Additions Pending Determination of Proved Reserves	$ (28,011)	$ (38,387)
Wells to be completed | Wells	4	2
Geological and geophysical	$ 3,017	$ 3,401	3,881
Other expenses	1,037	2,690	2,156
Exploration, geologic and geophysical expense	4,054	6,204	47,334
Property, Plant and Equipment, Net	4,095,202	4,002,862
Exploration and Production Equipment [Member]
Property, Plant and Equipment [Line Items]
Exploration, geologic and geophysical expense	$ 4,054	6,204	$ 47,334
Midstream [Member] [Member]
Property, Plant and Equipment [Line Items]
Assets Held-for-sale, Not Part of Disposal Group, Other		3,257
Utica Shale [Member]
Property, Plant and Equipment [Line Items]
Properties and equipment, net		137,448
Assets		140,705
Asset retirement obligations		4,111
Liabilities		$ 4,111