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
Mar. 31, 2017
Mar. 31, 2016
Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]      
Equity investments and investments in subsidiaries $ 251,370   $ 243,920
(Income) loss from equity method investments $ 4,907 $ 30,737  
Investment in Tatex Thailand II, LLC      
Schedule of Equity Method Investments [Line Items]      
Approximate ownership % 23.50%    
Equity investments and investments in subsidiaries $ 0   0
(Income) loss from equity method investments $ (243) (159)  
Investment in Tatex Thailand III, LLC      
Schedule of Equity Method Investments [Line Items]      
Approximate ownership % 17.90%    
Equity investments and investments in subsidiaries $ 0   0
(Income) loss from equity method investments $ 0 0  
Investment in Grizzly Oil Sands ULC      
Schedule of Equity Method Investments [Line Items]      
Approximate ownership % 24.9999%    
Equity investments and investments in subsidiaries $ 46,838   45,213
(Income) loss from equity method investments $ 365 23,685  
Investment in Timber Wolf Terminals LLC      
Schedule of Equity Method Investments [Line Items]      
Approximate ownership % 50.00%    
Equity investments and investments in subsidiaries $ 987   991
(Income) loss from equity method investments $ 4 3  
Investment in Windsor Midstream LLC      
Schedule of Equity Method Investments [Line Items]      
Approximate ownership % 22.50%    
Equity investments and investments in subsidiaries $ 25,815   25,749
(Income) loss from equity method investments $ (311) (167)  
Investment in Stingray Cementing LLC      
Schedule of Equity Method Investments [Line Items]      
Approximate ownership % 50.00%    
Equity investments and investments in subsidiaries $ 1,768   1,920
(Income) loss from equity method investments $ 128 30  
Investment in Blackhawk Midstream LLC      
Schedule of Equity Method Investments [Line Items]      
Approximate ownership % 48.50%    
Equity investments and investments in subsidiaries $ 0   0
(Income) loss from equity method investments $ 0 0  
Investment in Stingray Energy Services LLC      
Schedule of Equity Method Investments [Line Items]      
Approximate ownership % 50.00%    
Equity investments and investments in subsidiaries $ 3,967   4,215
(Income) loss from equity method investments $ 197 502  
Investment in Sturgeon Acquisitions LLC      
Schedule of Equity Method Investments [Line Items]      
Approximate ownership % 25.00%    
Equity investments and investments in subsidiaries $ 20,458   20,526
(Income) loss from equity method investments $ 68 377  
Investment in Mammoth Energy Services, Inc.      
Schedule of Equity Method Investments [Line Items]      
Approximate ownership % 24.20%    
Equity investments and investments in subsidiaries $ 110,875   111,717
(Income) loss from equity method investments $ 2,158 6,466  
Investment in Strike Force Midstream LLC      
Schedule of Equity Method Investments [Line Items]      
Approximate ownership % 25.00%    
Equity investments and investments in subsidiaries $ 40,662   $ 33,589
(Income) loss from equity method investments $ 2,541 $ 0