Derivative Financial Instruments Gains and Losses (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Gain and loss from derivative cash settlements and changes in fair value of derivative contracts
Derivative Settlement (Gain) Loss	$ (161,229)	[1]	$ 28,940	[1]
Derivative Instruments Not Designated as Hedging Instruments, (Gain) Loss, Net	(154,167)	[2]	97,662	[2]
Crude oil
Gain and loss from derivative cash settlements and changes in fair value of derivative contracts
Derivative Settlement (Gain) Loss	(106,214)		6,758
Derivative Instruments Not Designated as Hedging Instruments, (Gain) Loss, Net	(73,860)		31,950
Natural Gas
Gain and loss from derivative cash settlements and changes in fair value of derivative contracts
Derivative Settlement (Gain) Loss	(34,232)		13,404
Derivative Instruments Not Designated as Hedging Instruments, (Gain) Loss, Net	(82,339)		59,461
Natural Gas Liquids
Gain and loss from derivative cash settlements and changes in fair value of derivative contracts
Derivative Settlement (Gain) Loss	(20,783)		8,778
Derivative Instruments Not Designated as Hedging Instruments, (Gain) Loss, Net	$ 2,032		$ 6,251

[1] (1) Total derivative settlement (gain) loss is reported net of the change in accrued settlements between periods in the derivative cash settlements line item on the condensed consolidated statements of cash flows within net cash provided by operating activities.

[2] (2) Total derivative (gain) loss is reported in the derivative (gain) loss line item on the condensed consolidated statements of cash flows within net cash provided by operating activities.