Impairments (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Impaired Long-Lived Assets Held and Used [Line Items]
Impairments		$ 1,397,424	$ 791,809	$ 132,224
Impairment of Long-Lived Assets Held-for-use		1,396,340	791,809	132,224
Other Asset Impairment Charges		1,084	0	0
Eagle Ford Shale, Lavaca County [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Long-Lived Assets Held-for-use		1,400,000
East Texas, Granite Wash and Marcellus regions
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Long-Lived Assets Held-for-use			667,800
Mid-Continent region
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Oil and Gas Properties		6,100
Granite Wash
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Long-Lived Assets Held-for-use			$ 121,800
Selma Chalk
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Long-Lived Assets Held-for-use				900
Impairment of Oil and Gas Properties	$ 117,900	117,900
Marcellus Shale
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Long-Lived Assets Held-for-use				$ 9,500
Tubular Goods
Impaired Long-Lived Assets Held and Used [Line Items]
Other Asset Impairment Charges		1,100
Fair Value, Measurements, Nonrecurring
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Long-Lived Assets Held-for-use		$ 312,000