v3.8.0.1
Summary of Significant Accounting Policies - Additional Information (Detail)
 1 Months Ended 12 Months Ended
Jan. 01, 2018
USD ($)
Jan. 02, 2016
USD ($)
Apr. 30, 2017
USD ($)
Dec. 31, 2017
USD ($)
Segment
Dec. 31, 2016
USD ($)
Well
Dec. 31, 2015
USD ($)
Well
Summary Of Significant Accounting Policies [Line Items]            
Number of exploratory wells capitalized | Well         0 0
Capitalized interest cost       $ 0    
Depreciation depletion and amortization for oil & gas       70,300,000 $ 78,700,000 $ 108,800,000
Impairment of oil and gas properties and equipment       0 0 220,197,000
Depreciation expense for other property and equipment       $ 237,000 343,000 563,000
Tax benefit       50.00%    
Uncertain tax positions       $ 0 0  
Valuation allowance on deferred tax assets after accounting for change in corporate federal income tax rate under tax cuts and job act       500,000    
Prepayment under the agreement     $ 5,000,000      
Utilization of prepayment related to hydraulic fracturing services provided       700,000    
Prepaid expenses and other current assets       $ 5,486,000 2,834,000  
Number of days in which payment is to be made       30 days    
Exploration expenses       $ 3,657,000 $ 3,923,000 $ 4,439,000
Number of business segment | Segment       1    
New Accounting Pronouncement, Early Adoption, Effect [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Increase in accumulated earnings   $ 1,700,000        
Customer Concentration Risk [Member] | DCP Midstream, LLC [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Sales to customers       47.00% 46.00% 36.00%
Customer Concentration Risk [Member] | JP Energy Permian, LLC [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Sales to customers       52.00% 54.00% 63.00%
Drilling Contracts [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Exploration expenses         $ 2,200,000  
Subsequent Event [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Prepayment additional used amount $ 500,000          
Unused Prepaid Balance [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Prepaid expenses and other current assets       $ 4,300,000    
Unused Prepaid Balance [Member] | Subsequent Event [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Proceeds from prepayment under the agreement $ 3,800,000          
Minimum [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Estimated useful lives of furniture, fixtures and equipment       3 years    
Minimum [Member] | Oil and Gas [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Number of days in which payment is to be made       30 days    
Maximum [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Estimated useful lives of furniture, fixtures and equipment       15 years    
Maximum [Member] | Oil and Gas [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Number of days in which payment is to be made       60 days    
Proved Property Impairment [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Impairment of oil and gas properties and equipment       $ 0 0 $ 214,700,000
Unproved Property Impairment [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Impairment of oil and gas properties and equipment       $ 0 $ 0 $ 5,500,000