Description of Business and Significant Accounting Policies - Narrative (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Oct. 12, 2016
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Transfers from unevaluated to proved oil and natural gas properties	$ 100,000	$ 10,900,000
Full Cost Ceiling Test write-downs	$ 0	$ 0
13.5% Convertible Second Lien Notes [Member]
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Stated interest rate	13.50%		13.50%
Minimum [Member]
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Estimated useful lives	3 years
Maximum [Member]
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Estimated useful lives	5 years