Derivative Financial Instruments Fair Value (Details) $ in Thousands	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018
Fair value of derivative assets and liabilities
Derivative, Fair Value, Net	$ (168,200)	$ 21,500
Derivative Assets, Current	31,203	55,184
Derivative Assets, Noncurrent	23,150	20,624
Total Derivative Assets	54,353	75,808
Derivative Liabilities, Current	200,189	50,846
Derivative Liabilities, Noncurrent	22,331	3,444
Total Derivative Liabilities	(222,520)	(54,290)
Derivative Asset, Not Offset in the Accompanying Balance Sheets	(53,598)	(35,075)
Derivative Liabilities, Not Offset in the Accompanying Balance Sheets	53,598	35,075
Derivative Asset, Fair Value, Net Amounts	755	40,733
Derivative Liabilities, Fair Value, Net Amounts	(168,922)	(19,215)
Not Designated as Hedging Instrument [Member]
Fair value of derivative assets and liabilities
Derivative Assets, Current	31,203	55,184
Derivative Assets, Noncurrent	23,150	20,624
Derivative Liabilities, Current	200,189	50,846
Derivative Liabilities, Noncurrent	22,331	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	54,353	75,808
Total Derivative Liabilities	$ 222,520	$ 54,290
Designated as Hedging Instrument [Member]
Fair value of derivative assets and liabilities
Derivative, Number of Instruments Held	0	0	0

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