Quarterly report pursuant to Section 13 or 15(d)

Equity Investments (Narrative) (Details)

v3.8.0.1
Equity Investments (Narrative) (Details)
$ / shares in Units, a in Thousands, shares in Millions
 1 Months Ended 3 Months Ended 12 Months Ended
Jun. 05, 2017
USD ($)
$ / shares
shares
Dec. 31, 2017
USD ($)
Mar. 31, 2018
USD ($)
a
project
Mar. 31, 2017
USD ($)
Dec. 31, 2014
entity
Sep. 30, 2014
a
Dec. 31, 2014
USD ($)
Feb. 17, 2017
$ / shares
Dec. 15, 2016
$ / shares
Apr. 30, 2015
bbl
Mar. 31, 2015
Jun. 30, 2014
bbl
Schedule of Equity Method Investments [Line Items]                        
Income (loss) from equity method investments and investments in subsidiaries     $ 13,536,000 $ (4,907,000)                
Distributions from equity method investments     750,000 631,000                
Payments for equity method investments     1,569,000 10,673,000                
Share price (in dollars per share) | $ / shares               $ 19.48 $ 20.96      
Tatex Thailand III LLC                        
Schedule of Equity Method Investments [Line Items]                        
Distributions from equity method investments   $ 200,000                    
Tatex Thailand II, LLC                        
Schedule of Equity Method Investments [Line Items]                        
Income (loss) from equity method investments and investments in subsidiaries     $ 41,000 243,000                
Equity method investment, ownership interest, percent     23.50%                  
Grizzly Oil Sands ULC                        
Schedule of Equity Method Investments [Line Items]                        
Gas and oil area, reserve (acres) | a     830                  
Income (loss) from equity method investments and investments in subsidiaries     $ (330,000) (365,000)                
Number of oil sand projects | project     3                  
Production volume (in Bbls/day) | bbl                   2,200   11,300
Other than temporary impairment loss     $ 0 0                
Equity method investment, amount of cash calls, based on proportionate ownership interest     1,600,000                  
Equity method investments, increase (decrease) due to foreign currency translation adjustment     $ (5,300,000) 1,300,000                
Equity method investment, ownership interest, percent     24.9999%                  
Windsor Midstream LLC                        
Schedule of Equity Method Investments [Line Items]                        
Income (loss) from equity method investments and investments in subsidiaries     $ 0 311,000                
Distributions from equity method investments     $ 0 200,000                
Equity method investment, ownership interest, percent     22.50%                  
Coronado Midstream LLC | Windsor Midstream LLC                        
Schedule of Equity Method Investments [Line Items]                        
Equity method investment, ownership interest, percent                     28.40%  
Sturgeon Acquisitions LLC                        
Schedule of Equity Method Investments [Line Items]                        
Income (loss) from equity method investments and investments in subsidiaries     $ 0 (68,000)                
Equity method investment, ownership interest, percent     0.00%   25.00%   25.00%          
Payments for equity method investments             $ 20,700,000          
Gain on sale of equity method investments $ 12,500,000                      
Mammoth Energy Services LP                        
Schedule of Equity Method Investments [Line Items]                        
Equity method investments, increase (decrease) due to foreign currency translation adjustment     $ (200,000) 100,000                
Equity method investment, ownership interest, percent     25.10%   30.50%   30.50%          
Number of entities contributed for ownership interest | entity         4              
Shares received from equity method investee in exchange for ownership interest (in shares) | shares 2.0                      
Share price (in dollars per share) | $ / shares $ 18.50                      
Strike Force Midstream LLC                        
Schedule of Equity Method Investments [Line Items]                        
Income (loss) from equity method investments and investments in subsidiaries     $ 357,000 (2,541,000)                
Distributions from equity method investments     $ 800,000 400,000                
Equity method investment, ownership interest, percent   25.00% 25.00%                  
Payments for equity method investments       $ 10,000,000                
Phu Horm Field | Apico Llc                        
Schedule of Equity Method Investments [Line Items]                        
Gas and oil area, reserve (acres) | a     180                  
Concession Acreage in Southeast Asia | Tatex Thailand III LLC                        
Schedule of Equity Method Investments [Line Items]                        
Gas and oil area, reserve (acres) | a           245            
Apico Llc | Tatex Thailand II, LLC                        
Schedule of Equity Method Investments [Line Items]                        
Ownership percentage     8.50%                  
Strike Force Midstream LLC | Rice Energy Inc                        
Schedule of Equity Method Investments [Line Items]                        
Ownership percentage by parent   75.00%