Quarterly report pursuant to Section 13 or 15(d)

Equity Investments (Investments Accounted for by the Equity Method) (Details)

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Equity Investments (Investments Accounted for by the Equity Method) (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Dec. 31, 2016
Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]            
Equity investments and investments in subsidiaries $ 256,265   $ 256,265   $ 243,920  
(Income) loss from equity method investments $ 13,301 $ 836 $ 18,208 $ 31,573    
Investment in Tatex Thailand II, LLC            
Schedule of Equity Method Investments [Line Items]            
Approximate ownership % 23.50%   23.50%      
Equity investments and investments in subsidiaries $ 0   $ 0   0  
(Income) loss from equity method investments $ (211) 0 $ (454) (159)    
Investment in Tatex Thailand III, LLC            
Schedule of Equity Method Investments [Line Items]            
Approximate ownership % 17.90%   17.90%      
Equity investments and investments in subsidiaries $ 0   $ 0   0  
(Income) loss from equity method investments $ 0 0 $ 0 0    
Investment in Grizzly Oil Sands ULC            
Schedule of Equity Method Investments [Line Items]            
Approximate ownership % 24.9999%   24.9999%      
Equity investments and investments in subsidiaries $ 51,604   $ 51,604   45,213  
(Income) loss from equity method investments $ 208 763 $ 573 24,448    
Investment in Timber Wolf Terminals LLC            
Schedule of Equity Method Investments [Line Items]            
Approximate ownership % 50.00%   50.00%      
Equity investments and investments in subsidiaries $ 987   $ 987   991  
(Income) loss from equity method investments $ 0 1 $ 4 4    
Investment in Windsor Midstream LLC            
Schedule of Equity Method Investments [Line Items]            
Approximate ownership % 22.50%   22.50%      
Equity investments and investments in subsidiaries $ 270   $ 270   25,749  
(Income) loss from equity method investments $ 25,545 (2,881) $ 25,234 (3,048)    
Investment in Stingray Cementing LLC            
Schedule of Equity Method Investments [Line Items]            
Approximate ownership % 0.00%   0.00%      
Equity investments and investments in subsidiaries $ 0   $ 0   1,920  
(Income) loss from equity method investments $ 77 78 $ 205 108    
Investment in Blackhawk Midstream LLC            
Schedule of Equity Method Investments [Line Items]            
Approximate ownership % 48.50%   48.50%      
Equity investments and investments in subsidiaries $ 0   $ 0   0  
(Income) loss from equity method investments $ 0 0 $ 0 0    
Investment in Stingray Energy Services LLC            
Schedule of Equity Method Investments [Line Items]            
Approximate ownership % 0.00%   0.00%      
Equity investments and investments in subsidiaries $ 0   $ 0   4,215  
(Income) loss from equity method investments $ 85 139 $ 282 641    
Investment in Sturgeon Acquisitions LLC            
Schedule of Equity Method Investments [Line Items]            
Approximate ownership % 0.00%   0.00%     25.00%
Equity investments and investments in subsidiaries $ 0   $ 0   20,526  
(Income) loss from equity method investments $ (139) 134 $ (71) 511    
Investment in Mammoth Energy Services, Inc.            
Schedule of Equity Method Investments [Line Items]            
Approximate ownership % 25.10%   25.10%      
Equity investments and investments in subsidiaries $ 150,458   $ 150,458   111,717  
(Income) loss from equity method investments $ (12,181) 2,543 $ (10,023) 9,009    
Investment in Strike Force Midstream LLC            
Schedule of Equity Method Investments [Line Items]            
Approximate ownership % 25.00%   25.00%      
Equity investments and investments in subsidiaries $ 52,946   $ 52,946   $ 33,589  
(Income) loss from equity method investments $ (83) $ 59 $ 2,458 $ 59