Derivative Instruments and Fair Value Measurements - Narrative (Details) - Commodity Contract	12 Months Ended
	Dec. 31, 2018 barrel_of_oil_per_day contract	Dec. 31, 2017 barrel_of_oil_per_day contract
Derivative [Line Items]
Number of contracts held | contract	10	20
Reported Value Measurement
Derivative [Line Items]
Number of contracts held | contract		4
January through April 2019
Derivative [Line Items]
Production per day	322
May 2019
Derivative [Line Items]
Production per day	258
June 2019 through August 2019
Derivative [Line Items]
Production per day	322
September 2019 through December 2019
Derivative [Line Items]
Production per day	258
January 2018
Derivative [Line Items]
Production per day		452
February through May 2018
Derivative [Line Items]
Production per day		322
June 2018
Derivative [Line Items]
Production per day		258
July 2018
Derivative [Line Items]
Production per day		646
August through September 2018
Derivative [Line Items]
Production per day		322
October through December 2018
Derivative [Line Items]
Production per day		258