Derivative Financial Instruments Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2015		Dec. 31, 2014
Fair value of derivative assets and liabilities
Price Risk Derivatives, at Fair Value, Net	$ 391,400		$ 592,100
Derivative asset current	269,022		402,668
Derivative asset noncurrent	131,464		189,540
Derivative Asset, Fair Value, Gross Asset	400,486		592,208
Derivative liability, current	8,107		0
Derivatives liability noncurrent	1,026		70
Derivative Liability, Fair Value, Gross Liability	9,133		70
Derivatives not designated as hedging instruments
Fair value of derivative assets and liabilities
Derivative asset current	269,022		402,668
Derivative asset noncurrent	131,464		189,540
Derivative liability, current	8,107		0
Derivatives liability noncurrent	1,026		70
Fair Value, Inputs, Level 2 [Member] | Derivatives not designated as hedging instruments | Fair Value, Measurements, Recurring [Member]
Fair value of derivative assets and liabilities
Derivative Asset, Fair Value, Gross Asset	400,486	[1]	592,208	[2]
Derivative Liability, Fair Value, Gross Liability	$ 9,133	[1]	$ 70	[2]

[1] This represents a financial asset or liability that is measured at fair value on a recurring basis.

[2] This represents a financial asset or liability that is measured at fair value on a recurring basis.