Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements - Narrative (Details)

v3.6.0.2
Fair Value Measurements - Narrative (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Mar. 31, 2016
Feb. 01, 2016
Nov. 24, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Asset retirement obligation capitalized $ 10,971 $ 8,800 $ 9,295      
Mammoth Energy Partners LP            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Fair value of equity investment     143,500      
Strike Force Midstream LLC            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Fair value of equity investment     $ 22,500      
Level 3            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Asset retirement obligation capitalized $ 11,000          
Level 3 | Mammoth Energy Partners LP            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Fair value of equity investment           $ 143,500
Level 3 | Investment in Grizzly Oil Sands ULC            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Fair value of equity investment       $ 39,100    
Level 3 | Strike Force Midstream LLC            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Fair value of equity investment         $ 22,500