Derivative Financial Instruments Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2016		Dec. 31, 2015
Fair value of derivative assets and liabilities
Derivative, Fair Value, Net	$ 355,600		$ 488,400
Derivative asset current	281,596		367,710
Derivative asset noncurrent	160,732		120,701
Derivative Asset, Fair Value, Gross Asset	442,328		488,411
Derivative liability	8,211		8
Derivatives liability noncurrent	78,514		0
Derivative Liability, Fair Value, Gross Liability	86,725		8
Derivatives not designated as hedging instruments
Fair value of derivative assets and liabilities
Derivative asset current	281,596		367,710
Derivative asset noncurrent	160,732		120,701
Derivative liability	8,211		8
Derivatives liability noncurrent	78,514		0
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	442,328	[1]	488,411	[2]
Derivative Liability, Fair Value, Gross Liability	$ 86,725	[1]	$ 8	[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.