Derivative Instruments--Outstanding Derivatives (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jun. 30, 2014		Jun. 30, 2013
Swaps | Derivatives Maturing in 2014 | Oil Derivative
Derivative [Line Items]
Volume of derivative instruments held	369,000
Weighted average fixed price per unit, swaps	91.89
Swaps | Derivatives Maturing in 2014 | Natural Gas Derivative
Derivative [Line Items]
Volume of derivative instruments held	10,280,000
Weighted average fixed price per unit, swaps	4.05
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
Swaps | Derivatives Maturing in 2016 | Natural Gas Derivative
Derivative [Line Items]
Volume of derivative instruments held	7,800,000
Weighted average fixed price per unit, swaps	4.33
Costless Collars | Derivatives Maturing in 2014 | Oil Derivative
Derivative [Line Items]
Volume of derivative instruments held	1,200,000
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	420,000
Weighted average fixed price per unit, swaps	97.89
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
Enhanced Swaps | Derivatives Maturing in 2016 | Oil Derivative
Derivative [Line Items]
Volume of derivative instruments held	2,760,000
Weighted average fixed price per unit, swaps	92.25
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	1,415,000
Weighted average fixed price per unit, swaps	93.93
Weighted average fixed price per Bbl, sold puts	80.00
Weighted average fixed price per Bbl, purchased puts	60.00
Purchased Puts | Oil Derivative
Derivative [Line Items]
Premium paid for put options on commodity derivative contracts	$ 1,220		$ 664
Purchased Puts | Derivatives Maturing in 2014 | Oil Derivative
Derivative [Line Items]
Volume of derivative instruments held	420,000	[1]	840,000
Weighted average fixed price per Bbl, purchased puts	60.00	[1]
Purchased Puts | Derivatives Maturing in 2015 | Oil Derivative
Derivative [Line Items]
Volume of derivative instruments held	5,548,000	[1]
Weighted average fixed price per Bbl, purchased puts	60.00	[1]
Basis Protection Swaps | Derivatives Maturing in 2014 | Natural Gas Derivative
Derivative [Line Items]
Volume of derivative instruments held	10,440,000
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

[1] Puts covering 840 Mbbls in 2014 were purchased during the second quarter of 2013 for $664. The 2015 puts were purchased during the second quarter of 2014 for $1,220.