Derivative Financial Instruments Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2020		Dec. 31, 2019
Fair value of derivative assets and liabilities
Derivative, fair value, net	$ 493,400		$ 21,500
Derivative assets, current	463,992		55,184
Derivative assets, noncurrent	44,909		20,624
Total derivative assets	508,901		75,808
Derivative liabilities, current	8,277		50,846
Derivatives liabilities, noncurrent	7,202		3,444
Total derivative liabilities	(15,479)		(54,290)
Derivative asset, amounts not offset in the accompanying balance sheets	(15,479)		(35,075)
Derivative liabilities, amounts not offset in the accompanying balance sheets	15,479		35,075
Derivative asset, fair value, net amounts	493,422		40,733
Derivative liabilities, fair value, net amounts	0		(19,215)
Not Designated as Hedging Instrument [Member]
Fair value of derivative assets and liabilities
Derivative assets, current	463,992		55,184
Derivative assets, noncurrent	44,909		20,624
Derivative liabilities, current	8,277		50,846
Derivatives liabilities, noncurrent	7,202		3,444
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Not Designated as Hedging Instrument [Member]
Fair value of derivative assets and liabilities
Total derivative assets	508,901	[1]	75,808	[2]
Total derivative liabilities	$ 15,479	[1]	$ 54,290	[2]

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

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