Divestitures, Assets Held for Sale, and Acquisitions Divestitures and Assets Held for Sale (Details) - USD ($) $ in Thousands		3 Months Ended				6 Months Ended		7 Months Ended
		Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net proceeds from the sale of oil and gas properties						$ 766,247	$ 12,967
Net gain (loss) on divestiture activity		$ (167,133)		$ 50,046		(129,670)	(18,975)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest		(190,968)		(264,579)		(72,028)	(806,664)
Impairment of Proved Oil and Gas Properties		3,806		0		3,806	269,785
Disposal Group, Including Discontinued Operation, Assets, Current		18,739				18,739		$ 18,739	$ 372,621
Disposal Group, Not Discontinued Operation, Loss (Gain) on Write-down				(49,500)	$ 68,300
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Non-Operated Eagle Ford Divestiture 2017 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net proceeds from the sale of oil and gas properties						747,400
Net gain (loss) on divestiture activity						397,400
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	[1]	0		$ 12,832		24,324	(273,567)
Impairment of Proved Oil and Gas Properties							$ 269,600
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Divide County Divestiture 2017 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net proceeds from the sale of oil and gas properties		24,600
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Raven/Bear Den Divestiture 2016 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain (loss) on divestiture activity								$ 29,100
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Divide County Disposal Group [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment of Proved Oil and Gas Properties						$ 526,500
Disposal Group, Not Discontinued Operation, Loss (Gain) on Write-down		$ 166,900	$ 359,600

[1] Income (loss) before income taxes reflects oil, gas, and NGL production revenue, less oil, gas, and NGL production expense, and depletion, depreciation, amortization, and asset retirement obligation liability accretion. Additionally, income (loss) before income taxes included impairment of proved properties expense of approximately $269.6 million for the six months ended June 30, 2016.