Quarterly report pursuant to Section 13 or 15(d)

Contingencies - Additional Information (Details)

v3.10.0.1
Contingencies - Additional Information (Details)
$ in Thousands
 6 Months Ended 12 Months Ended
Jan. 27, 2017
USD ($)
Jun. 30, 2018
USD ($)
claim
Dec. 31, 2012
USD ($)
Dec. 31, 2017
USD ($)
Jun. 30, 2017
USD ($)
May 31, 2017
USD ($)
Dec. 15, 2014
DeepwaterWell
Dec. 31, 2010
USD ($)
Loss Contingencies [Line Items]                
Number of deepwater wells abandoned | DeepwaterWell             3  
Deposit Into registry of court   $ 49,500   $ 49,500        
Loss contingency accrued amount   49,500   49,500        
Additional royalty payment   300     $ 1,100     $ 4,700
Payments for royalty $ 4,700              
Bond requied to post in order to appeal 7,200              
Cash collacteral required to appeal $ 6,900              
Increase in liability reserve   $ 1,200            
Liability reserve     $ 900          
Royalty payment processing revised period   84 months            
BSEE                
Loss Contingencies [Line Items]                
Number of notices | claim   5            
Proposed civil penalties related to various incidents of noncompliance, total   $ 7,800            
Payments for civil penalty   3,400            
Apache Corporation | Judicial Ruling                
Loss Contingencies [Line Items]                
Amount owed to Apache under judicial decision           $ 43,200    
Prejudgment interest, attorney fees and judgment costs           $ 6,300    
Apache Corporation | Judicial Ruling | Other Noncurrent Assets                
Loss Contingencies [Line Items]                
Deposit Into registry of court   49,500   49,500        
Apache Corporation | Judicial Ruling | Other Noncurrent Liabilities                
Loss Contingencies [Line Items]                
Loss contingency accrued amount   $ 49,500   $ 49,500