Quarterly report pursuant to Section 13 or 15(d)

Commitments And Contingencies (Detail)

v3.5.0.2
Commitments And Contingencies (Detail)
3 Months Ended 9 Months Ended 12 Months Ended
Apr. 20, 2016
USD ($)
Dec. 31, 2016
USD ($)
Jun. 30, 2015
USD ($)
Sep. 30, 2016
USD ($)
item
Dec. 31, 2015
USD ($)
Jun. 30, 2016
USD ($)
Commitments And Contingencies [Line Items]            
Number Monthly Payments | item       7    
Contractual Obligation Company Share       $ 3,600,000   $ 5,100,000
Abandonment Funding       5,137,000 $ 5,137,000  
Abandonment cost related to annual funding         61,100,000  
Abandonment cost related to annual funding, net         17,300,000  
DGH audit settlement     $ 300,000      
Payments for Legal Settlements $ 775,000          
Scenario, Forecast [Member]            
Commitments And Contingencies [Line Items]            
Abandonment cost related to annual funding   $ 9,100,000        
Abandonment cost related to annual funding, net   $ 2,600,000        
Gabon [Member]            
Commitments And Contingencies [Line Items]            
Abandonment Funding         5,100,000  
Abandonment funding, gross         $ 18,300,000  
Accrued Payroll Taxes       $ 2,200,000