Derivative Instruments and Hedging Activities - Hedging Positions (Details)	9 Months Ended
	Sep. 30, 2017 $ / bbl $ / MMBTU bbl / mo MMBTU / mo
Oil | Swaps | Low
Hedging Positions
Exercise price (in dollars per barrel)	44.60
Offset exercise price (in dollars per barrel)	42.00
Net barrels per month (in barrels per month) | bbl / mo	55,000
Oil | Swaps | High
Hedging Positions
Exercise price (in dollars per barrel)	85.60
Offset exercise price (in dollars per barrel)	42.00
Net barrels per month (in barrels per month) | bbl / mo	216,000
Oil | Swaps | Weighted Average
Hedging Positions
Exercise price (in dollars per barrel)	51.97
Offset exercise price (in dollars per barrel)	42.00
Net barrels per month (in barrels per month) | bbl / mo	116,462
Oil | Collars | Low
Hedging Positions
Net barrels per month (in barrels per month) | bbl / mo	65,000
Oil | Collars | High
Hedging Positions
Net barrels per month (in barrels per month) | bbl / mo	73,000
Oil | Collars | Weighted Average
Hedging Positions
Net barrels per month (in barrels per month) | bbl / mo	67,500
Natural gas | Swaps | Low
Hedging Positions
Exercise price (in dollars per mmbtu) | $ / MMBTU	2.76
Net mmbtu per month (in mmbtu per month) | MMBTU / mo	700,000
Natural gas | Swaps | High
Hedging Positions
Exercise price (in dollars per mmbtu) | $ / MMBTU	4.57
Net mmbtu per month (in mmbtu per month) | MMBTU / mo	1,890,000
Natural gas | Swaps | Weighted Average
Hedging Positions
Exercise price (in dollars per mmbtu) | $ / MMBTU	2.98
Net mmbtu per month (in mmbtu per month) | MMBTU / mo	1,169,231
Natural gas | Collars | Low
Hedging Positions
Net barrels per month (in barrels per month) | bbl / mo	950,000
Natural gas | Collars | High
Hedging Positions
Net barrels per month (in barrels per month) | bbl / mo	1,050,000
Natural gas | Collars | Weighted Average
Hedging Positions
Net barrels per month (in barrels per month) | bbl / mo	990,833
Natural gas | Basis swaps | Low
Hedging Positions
Offset exercise price (in dollars per mmbtu) | $ / MMBTU	(0.50)
Net mmbtu per month (in mmbtu per month) | MMBTU / mo	300,000
Natural gas | Basis swaps | High
Hedging Positions
Offset exercise price (in dollars per mmbtu) | $ / MMBTU	(0.30)
Net mmbtu per month (in mmbtu per month) | MMBTU / mo	800,000
Natural gas | Basis swaps | Weighted Average
Hedging Positions
Offset exercise price (in dollars per mmbtu) | $ / MMBTU	(0.39)
Net mmbtu per month (in mmbtu per month) | MMBTU / mo	564,706
Natural gas liquids | Swaps | Low
Hedging Positions
Exercise price (in dollars per barrel)	18.06
Net barrels per month (in barrels per month) | bbl / mo	130,000
Natural gas liquids | Swaps | High
Hedging Positions
Exercise price (in dollars per barrel)	72.52
Net barrels per month (in barrels per month) | bbl / mo	145,000
Natural gas liquids | Swaps | Weighted Average
Hedging Positions
Exercise price (in dollars per barrel)	29.08
Net barrels per month (in barrels per month) | bbl / mo	139,333
Puts (floors) | Oil | Collars | Low
Hedging Positions
Exercise price (in dollars per barrel)	45.00
Puts (floors) | Oil | Collars | High
Hedging Positions
Exercise price (in dollars per barrel)	50.00
Puts (floors) | Oil | Collars | Weighted Average
Hedging Positions
Exercise price (in dollars per barrel)	48.52
Puts (floors) | Natural gas | Collars | Low
Hedging Positions
Exercise price (in dollars per mmbtu)	2.55
Puts (floors) | Natural gas | Collars | High
Hedging Positions
Exercise price (in dollars per mmbtu)	2.55
Puts (floors) | Natural gas | Collars | Weighted Average
Hedging Positions
Exercise price (in dollars per mmbtu)	2.55
Calls (ceilings) | Oil | Collars | Low
Hedging Positions
Exercise price (in dollars per barrel)	56.60
Calls (ceilings) | Oil | Collars | High
Hedging Positions
Exercise price (in dollars per barrel)	61.00
Calls (ceilings) | Oil | Collars | Weighted Average
Hedging Positions
Exercise price (in dollars per barrel)	59.64
Calls (ceilings) | Natural gas | Collars | Low
Hedging Positions
Exercise price (in dollars per mmbtu)	3.08
Calls (ceilings) | Natural gas | Collars | High
Hedging Positions
Exercise price (in dollars per mmbtu)	3.41
Calls (ceilings) | Natural gas | Collars | Weighted Average
Hedging Positions
Exercise price (in dollars per mmbtu)	3.19