Derivative Instruments--Outstanding Derivatives (Details)	Mar. 31, 2014 bbl
Swaps | Derivatives Maturing In 2014 | Oil Derivative
Derivative [Line Items]
Volume of derivative instruments held	581,000
Weighted average fixed price per unit, swaps	92.30
Swaps | Derivatives Maturing In 2014 | Natural Gas Derivative
Derivative [Line Items]
Volume of derivative instruments held	15,640,000
Weighted average fixed price per unit, swaps	4.01
Swaps | Derivatives maturing in 2015 | Natural Gas Derivative
Derivative [Line Items]
Volume of derivative instruments held	22,170,000
Weighted average fixed price per unit, swaps	4.20
Costless Collars | Derivatives Maturing In 2014 | Oil Derivative
Derivative [Line Items]
Volume of derivative instruments held	1,800,000
Weighted average fixed price per Bbl, sold puts	75.50
Weighted average fixed price per Bbl, purchased puts	93.25
Weighted average fixed price per Bbl, sold calls	101.94
Enhanced Swaps | Derivatives Maturing In 2014 | Oil Derivative
Derivative [Line Items]
Volume of derivative instruments held	630,000
Weighted average fixed price per unit, swaps	98.24
Weighted average fixed price per Bbl, sold puts	80.00
Enhanced Swaps | Derivatives maturing in 2015 | Oil Derivative
Derivative [Line Items]
Volume of derivative instruments held	6,058,000
Weighted average fixed price per unit, swaps	92.92
Weighted average fixed price per Bbl, sold puts	80.00
Put Spread Enhanced Swaps | Derivatives Maturing In 2014 | Oil Derivative
Derivative [Line Items]
Volume of derivative instruments held	2,072,000
Weighted average fixed price per unit, swaps	93.85
Weighted average fixed price per Bbl, sold puts	80.00
Weighted average fixed price per Bbl, purchased puts	60.00
Put Options Purchased | Derivatives Maturing In 2014 | Oil Derivative
Derivative [Line Items]
Volume of derivative instruments held	630,000
Weighted average fixed price per Bbl, purchased puts	60.00
Basis Protection Swaps | Derivatives Maturing In 2014 | Natural Gas Derivative
Derivative [Line Items]
Volume of derivative instruments held	16,120,000
Weighted average fixed price per unit, swaps	0.24
Basis Protection Swaps | Derivatives maturing in 2015 | Natural Gas Derivative
Derivative [Line Items]
Volume of derivative instruments held	2,400,000
Weighted average fixed price per unit, swaps	0.18