Contingencies and Commitments - Additional Information (Details)	1 Months Ended		12 Months Ended
	Jul. 31, 2019 USD ($)	Feb. 28, 2018 USD ($)	Dec. 31, 2018 USD ($) Drilling_Rig	Dec. 31, 2017 USD ($)
Loss Contingencies [Line Items]
Building rent expense			$ 412,000	$ 439,000
Number Of Drilling Rigs Under Contract | Drilling_Rig			2
Contract services to cover wells planned to be drilled | Drilling_Rig			14
Drilling Rig
Loss Contingencies [Line Items]
Aggregate drilling rate		$ 22,500
Drilling Rig | Subsequent Event
Loss Contingencies [Line Items]
Early termination fee amount	$ 0