XML 74 R60.htm IDEA: XBRL DOCUMENT v3.8.0.1
Claim Settlement Receivable (Details) - USD ($)
$ in Thousands
1 Months Ended 9 Months Ended 12 Months Ended
Mar. 24, 2016
Oct. 31, 2017
Oct. 31, 2016
Dec. 31, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Receivables with Imputed Interest [Line Items]              
Litigation settlement receivable due October 2019         $ 2,700    
Litigation settlement receivable       $ 7,804 5,280 $ 7,804  
Litigation settlement proceeds         0 12,548 $ 0
BP Exploration & Production Inc.              
Receivables with Imputed Interest [Line Items]              
Litigation settlement amount $ 13,200            
Litigation settlement amount received   $ 2,700 $ 5,000        
Litigation settlement receivable due in October 2018 $ 2,700            
Imputed interest rate on litigation settlement receivable 3.00%            
Litigation settlement receivable $ 12,500            
Unamortized discount $ 700            
Interest income, operating       $ 300 $ 200    
BP Exploration & Production Inc. | Other income              
Receivables with Imputed Interest [Line Items]              
Litigation settlement proceeds           $ 12,500