Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements (Details)

v3.4.0.3
Fair Value Measurements (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2016
Mar. 31, 2015
Feb. 01, 2016
Dec. 31, 2015
Liabilities:        
Asset retirement obligation capitalized $ 1,914 $ 1,584    
Equity investments 244,601     $ 242,393
Investment in Grizzly Oil Sands ULC        
Liabilities:        
Equity investment 39,054      
Equity investments       50,645
Investment in Strike Force Midstream LLC        
Liabilities:        
Equity investment 22,500      
Equity investments     $ 22,500 $ 0
Level 1        
Assets:        
Derivative Instruments 0      
Liabilities:        
Derivative Instruments 0      
Level 2        
Assets:        
Derivative Instruments 194,666      
Liabilities:        
Derivative Instruments 15,842      
Level 3        
Assets:        
Derivative Instruments 0      
Liabilities:        
Derivative Instruments 0      
Asset retirement obligation capitalized 1,900      
Level 3 | Investment in Grizzly Oil Sands ULC        
Liabilities:        
Equity investment $ 39,054