Derivatives - Summary of Derivative Instruments (Details) - Crude Oil - Subsequent Event ThousandBarrels / d in Thousands	Jul. 31, 2019 ThousandBarrels / d $ / Barrel
2020 Settlement
Derivative [Line Items]
Derivative instruments (mmbls/day) | ThousandBarrels / d	300
2020 Settlement | Short position
Derivative [Line Items]
Ceiling sold price (dollars per barrel)	74.09
Purchased price (dollars per barrel)	45.00
2020 Settlement | Long position
Derivative [Line Items]
Purchased price (dollars per barrel)	55.00
2021 Settlement
Derivative [Line Items]
Derivative instruments (mmbls/day) | ThousandBarrels / d	300
2021 Settlement | Short position
Derivative [Line Items]
Ceiling sold price (dollars per barrel)	74.09