Derivatives (Commodities) (Details) - Oil MBbls in Thousands	Dec. 31, 2016 MBbls $ / bbl
Derivative [Line Items]
MBbls | MBbls	407
Current Swap, First Quarter
Derivative [Line Items]
MBbls | MBbls	178
Swap, fixed price (in dollars per unit)	44.85
Current Swap, Second Quarter
Derivative [Line Items]
MBbls | MBbls	165
Swap, fixed price (in dollars per unit)	44.65
Current Swap, Third Quarter
Derivative [Line Items]
MBbls | MBbls	37
Swap, fixed price (in dollars per unit)	50.00
Current Swap, Fourth Quarter
Derivative [Line Items]
MBbls | MBbls	27
Swap, fixed price (in dollars per unit)	50.00
1st Quarter 2017
Derivative [Line Items]
MBbls | MBbls	355
Weighted average floor price (in dollars per unit)	42.26
Weighted average ceiling price (in dollars per unit)	51.67
2nd Quarter 2017
Derivative [Line Items]
MBbls | MBbls	354
Weighted average floor price (in dollars per unit)	42.27
Weighted average ceiling price (in dollars per unit)	51.67
3rd Quarter 2017
Derivative [Line Items]
MBbls | MBbls	356
Weighted average floor price (in dollars per unit)	42.27
Weighted average ceiling price (in dollars per unit)	51.65
4th Quarter 2017
Derivative [Line Items]
MBbls | MBbls	350
Weighted average floor price (in dollars per unit)	42.27
Weighted average ceiling price (in dollars per unit)	51.66
Crude Oil Costless Collar
Derivative [Line Items]
MBbls | MBbls	1,415