Acquisitions and Dispositions Acquisitions and Dispositions (Details) - USD ($) $ in Thousands		3 Months Ended
	Jan. 24, 2018	Mar. 31, 2019	Mar. 31, 2018	Dec. 22, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Payments for (Proceeds from) Other Investing Activities		$ 1,278	$ 6,042
AWP Olmos Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Sale of Oil and Gas Property and Equipment	$ 27,000
Buyer's Assumption of ARO	$ 6,300
Bay De Chene [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Purchase and sale contract				$ 16,300
Cash to be released for purchase and sale contract		$ 6,200