Acquisitions and Divestitures Acquisitions and Divestitures - Divestiture (Details) $ in Thousands		3 Months Ended			9 Months Ended
	Mar. 22, 2019 USD ($) a Boe well location	Sep. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on divestiture		$ (483)		$ 0	$ (33,530)	$ (1,568)
Pirate Divestiture
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture	$ 12,300
Net undeveloped acres (in acres) | a	3,400
Producing wells | well	6
Proved undeveloped locations | location	7
Production per day (in barrels of oil equivalent) | Boe	200
Gain (loss) on divestiture			$ (33,500)