Annual report pursuant to Section 13 and 15(d)

Derivative Instruments and Hedging Activities (Schedule of Outstanding Oil and Natural Gas Derivative Contracts) (Details)

v3.3.1.900
Derivative Instruments and Hedging Activities (Schedule of Outstanding Oil and Natural Gas Derivative Contracts) (Details) - Not Designated as Hedging Instrument [Member]
2 Months Ended 12 Months Ended
Feb. 29, 2016
MMBTU
$ / MMBTU
$ / bbl
MBbls
Dec. 31, 2015
$ / bbl
MBbls
Collar Contracts Combined With Short Puts Three Months Ended March 31, 2016 [Member] | Crude Oil [Member]    
Derivative [Line Items]    
Total volume | MBbls   182
Collar Contracts Combined With Short Puts Three Months Ended March 31, 2016 [Member] | Crude Oil [Member] | Subsequent Event [Member]    
Derivative [Line Items]    
Total volume | MBbls 120  
Collar Contracts Combined With Short Puts Three Months Ended March 31, 2016 [Member] | Crude Oil [Member] | Call Option [Member] | Short [Member]    
Derivative [Line Items]    
Strike price   65.00
Collar Contracts Combined With Short Puts Three Months Ended March 31, 2016 [Member] | Crude Oil [Member] | Call Option [Member] | Short [Member] | Subsequent Event [Member]    
Derivative [Line Items]    
Strike price 46.50  
Collar Contracts Combined With Short Puts Three Months Ended March 31, 2016 [Member] | Crude Oil [Member] | Put Option [Member] | Long [Member]    
Derivative [Line Items]    
Strike price   55.00
Collar Contracts Combined With Short Puts Three Months Ended March 31, 2016 [Member] | Crude Oil [Member] | Put Option [Member] | Long [Member] | Subsequent Event [Member]    
Derivative [Line Items]    
Strike price 37.50  
Collar Contracts Combined With Short Puts Three Months Ended March 31, 2016 [Member] | Crude Oil [Member] | Put Option [Member] | Short [Member]    
Derivative [Line Items]    
Strike price   40.33
Collar Contracts Combined With Short Puts Three Months Ended June 30, 2016 [Member] | Crude Oil [Member]    
Derivative [Line Items]    
Total volume | MBbls   182
Collar Contracts Combined With Short Puts Three Months Ended June 30, 2016 [Member] | Crude Oil [Member] | Subsequent Event [Member]    
Derivative [Line Items]    
Total volume | MBbls 182  
Collar Contracts Combined With Short Puts Three Months Ended June 30, 2016 [Member] | Crude Oil [Member] | Call Option [Member] | Short [Member]    
Derivative [Line Items]    
Strike price   65.00
Collar Contracts Combined With Short Puts Three Months Ended June 30, 2016 [Member] | Crude Oil [Member] | Call Option [Member] | Short [Member] | Subsequent Event [Member]    
Derivative [Line Items]    
Strike price 46.50  
Collar Contracts Combined With Short Puts Three Months Ended June 30, 2016 [Member] | Crude Oil [Member] | Put Option [Member] | Long [Member]    
Derivative [Line Items]    
Strike price   55.00
Collar Contracts Combined With Short Puts Three Months Ended June 30, 2016 [Member] | Crude Oil [Member] | Put Option [Member] | Long [Member] | Subsequent Event [Member]    
Derivative [Line Items]    
Strike price 37.50  
Collar Contracts Combined With Short Puts Three Months Ended June 30, 2016 [Member] | Crude Oil [Member] | Put Option [Member] | Short [Member]    
Derivative [Line Items]    
Strike price   40.33
Collar Contracts Combined With Short Puts Three Months Ended September 30, 2016 [Member] | Crude Oil [Member]    
Derivative [Line Items]    
Total volume | MBbls   184
Collar Contracts Combined With Short Puts Three Months Ended September 30, 2016 [Member] | Crude Oil [Member] | Subsequent Event [Member]    
Derivative [Line Items]    
Total volume | MBbls 184  
Collar Contracts Combined With Short Puts Three Months Ended September 30, 2016 [Member] | Crude Oil [Member] | Call Option [Member] | Short [Member]    
Derivative [Line Items]    
Strike price   65.00
Collar Contracts Combined With Short Puts Three Months Ended September 30, 2016 [Member] | Crude Oil [Member] | Call Option [Member] | Short [Member] | Subsequent Event [Member]    
Derivative [Line Items]    
Strike price 46.50  
Collar Contracts Combined With Short Puts Three Months Ended September 30, 2016 [Member] | Crude Oil [Member] | Put Option [Member] | Long [Member]    
Derivative [Line Items]    
Strike price   55.00
Collar Contracts Combined With Short Puts Three Months Ended September 30, 2016 [Member] | Crude Oil [Member] | Put Option [Member] | Long [Member] | Subsequent Event [Member]    
Derivative [Line Items]    
Strike price 37.50  
Collar Contracts Combined With Short Puts Three Months Ended September 30, 2016 [Member] | Crude Oil [Member] | Put Option [Member] | Short [Member]    
Derivative [Line Items]    
Strike price   40.33
Collar Contracts Combined With Short Puts Three Months Ended December 31, 2016 [Member] | Crude Oil [Member]    
Derivative [Line Items]    
Total volume | MBbls   184
Collar Contracts Combined With Short Puts Three Months Ended December 31, 2016 [Member] | Crude Oil [Member] | Subsequent Event [Member]    
Derivative [Line Items]    
Total volume | MBbls 184  
Collar Contracts Combined With Short Puts Three Months Ended December 31, 2016 [Member] | Crude Oil [Member] | Call Option [Member] | Short [Member]    
Derivative [Line Items]    
Strike price   65.00
Collar Contracts Combined With Short Puts Three Months Ended December 31, 2016 [Member] | Crude Oil [Member] | Call Option [Member] | Short [Member] | Subsequent Event [Member]    
Derivative [Line Items]    
Strike price 46.50  
Collar Contracts Combined With Short Puts Three Months Ended December 31, 2016 [Member] | Crude Oil [Member] | Put Option [Member] | Long [Member]    
Derivative [Line Items]    
Strike price   55.00
Collar Contracts Combined With Short Puts Three Months Ended December 31, 2016 [Member] | Crude Oil [Member] | Put Option [Member] | Long [Member] | Subsequent Event [Member]    
Derivative [Line Items]    
Strike price 37.50  
Collar Contracts Combined With Short Puts Three Months Ended December 31, 2016 [Member] | Crude Oil [Member] | Put Option [Member] | Short [Member]    
Derivative [Line Items]    
Strike price   40.33
Swap Contracts Three Months Ended March 31, 2016 [Member] | Crude Oil [Member]    
Derivative [Line Items]    
Total volume | MBbls   182
Average swap price   58.23
Swap Contracts Three Months Ended March 31, 2016 [Member] | Natural Gas [Member] | Swap [Member] | Subsequent Event [Member]    
Derivative [Line Items]    
Total volume | MMBTU 360  
Average swap price | $ / MMBTU 2.52  
Swap Contracts Three Months Ended June 30, 2016 [Member] | Crude Oil [Member]    
Derivative [Line Items]    
Total volume | MBbls   182
Average swap price   58.23
Swap Contracts Three Months Ended June 30, 2016 [Member] | Natural Gas [Member] | Swap [Member] | Subsequent Event [Member]    
Derivative [Line Items]    
Total volume | MMBTU 546  
Average swap price | $ / MMBTU 2.52  
Swap Contracts Three Months Ended September 30, 2016 [Member] | Crude Oil [Member]    
Derivative [Line Items]    
Total volume | MBbls   184
Average swap price   58.23
Swap Contracts Three Months Ended September 30, 2016 [Member] | Natural Gas [Member] | Swap [Member] | Subsequent Event [Member]    
Derivative [Line Items]    
Total volume | MMBTU 552  
Average swap price | $ / MMBTU 2.52  
Swap Contracts Three Months Ended December 31, 2016 [Member] | Crude Oil [Member]    
Derivative [Line Items]    
Total volume | MBbls   184
Average swap price   58.23
Swap Contracts Three Months Ended December 31, 2016 [Member] | Natural Gas [Member] | Swap [Member] | Subsequent Event [Member]    
Derivative [Line Items]    
Total volume | MMBTU 552  
Average swap price | $ / MMBTU 2.52  
Swap Contracts Differentials Three Months Ended March 31, 2016 [Member] | Crude Oil [Member]    
Derivative [Line Items]    
Total volume | MBbls   364
Swap Contracts Differentials Three Months Ended March 31, 2016 [Member] | Crude Oil [Member] | Swap [Member]    
Derivative [Line Items]    
Average swap price   0.17
Swap Contracts Differentials Three Months Ended June 30, 2016 [Member] | Crude Oil [Member]    
Derivative [Line Items]    
Total volume | MBbls   364
Swap Contracts Differentials Three Months Ended June 30, 2016 [Member] | Crude Oil [Member] | Swap [Member]    
Derivative [Line Items]    
Average swap price   0.17
Swap Contracts Differentials Three Months Ended September 30, 2016 [Member] | Crude Oil [Member]    
Derivative [Line Items]    
Total volume | MBbls   368
Swap Contracts Differentials Three Months Ended September 30, 2016 [Member] | Crude Oil [Member] | Swap [Member]    
Derivative [Line Items]    
Average swap price   0.17
Swap Contracts Differentials Three Months Ended December 31, 2016 [Member] | Crude Oil [Member]    
Derivative [Line Items]    
Total volume | MBbls   368
Swap Contracts Differentials Three Months Ended December 31, 2016 [Member] | Crude Oil [Member] | Swap [Member]    
Derivative [Line Items]    
Average swap price   0.17
Short Call Contracts Three Months March 31, 2017 [Member] | Crude Oil [Member] | Call Option [Member] | Subsequent Event [Member]    
Derivative [Line Items]    
Total volume | MBbls 165  
Strike price 50.00  
Short Call Contracts Three Months June 30, 2017 [Member] | Crude Oil [Member] | Call Option [Member] | Subsequent Event [Member]    
Derivative [Line Items]    
Total volume | MBbls 167  
Strike price 50.00  
Short Call Contracts Three Months September 30, 2017 [Member] | Crude Oil [Member] | Call Option [Member] | Subsequent Event [Member]    
Derivative [Line Items]    
Total volume | MBbls 169  
Strike price 50.00  
Short Short Call Contracts Three Months December 31, 2017 [Member] | Crude Oil [Member] | Call Option [Member] | Subsequent Event [Member]    
Derivative [Line Items]    
Total volume | MBbls 169  
Strike price 50.00