Annual report pursuant to Section 13 and 15(d)

Contingencies - Additional Information (Details)

v3.10.0.1
Contingencies - Additional Information (Details)
 12 Months Ended
Dec. 31, 2018
USD ($)
claim
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Jun. 30, 2017
USD ($)
May 31, 2017
USD ($)
Jan. 27, 2017
USD ($)
Dec. 15, 2014
DeepwaterWell
Dec. 31, 2010
USD ($)
Loss Contingencies [Line Items]                
Number of deepwater wells abandoned | DeepwaterWell             3  
Deposit Into registry of court $ 49,500,000 $ 49,500,000            
Loss contingency accrued amount 49,500,000 49,500,000            
Notified disallowed amount in reductions taken by ONRR           $ 4,700,000   $ 4,700,000
Bond requied to post in order to appeal           7,200,000    
Cash collateral required to appeal           $ 6,900,000    
Liability reserve $ 2,100,000              
Royalty payment processing revised period 84 months              
Royalties paid $ 600,000 1,600,000 $ 500,000          
Outstanding obligation to secure financial assurances upon rescindment 0              
BSEE                
Loss Contingencies [Line Items]                
Loss contingency accrued amount $ 3,500,000              
Number of notices | claim 9              
Proposed civil penalties related to various incidents of noncompliance, total $ 7,700,000              
Payments for civil penalty $ 0 200,000 $ 100,000          
Apache Corporation | Judicial Ruling                
Loss Contingencies [Line Items]                
Amount owed to Apache under judicial decision         $ 43,200,000      
Prejudgment interest, attorney fees and judgment costs         $ 6,300,000      
Apache Corporation | Judicial Ruling | Other Income/Expense                
Loss Contingencies [Line Items]                
Recognized prejudgment interest, attorney fees and judgment costs.   6,300,000            
Apache Corporation | Judicial Ruling | Asset Retirement Obligation                
Loss Contingencies [Line Items]                
Capitalized loss contingency damages payable to other party except attorney fees judgment costs and prejudgment interest   43,200,000            
Apache Corporation | Judicial Ruling | Other Noncurrent Assets                
Loss Contingencies [Line Items]                
Deposit Into registry of court       $ 49,500,000        
Apache Corporation | Judicial Ruling | Other Noncurrent Liabilities                
Loss Contingencies [Line Items]                
Loss contingency accrued amount   $ 49,500,000