Derivatives and Risk Management - Schedules of Fair Values and Locations of Derivative Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Gross Asset	$ 44,788	$ 24,702
Gross Liability	(86,787)	(83,280)
Collateral Netted	12,016	8,666
Net Asset (Liability) on Balance Sheet	(29,983)	(49,912)
Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Collateral Netted	6,166	616
Other Current Liabilities [Member] \| Foreign Exchange Contract [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	0
Gross Liability	(88)
Collateral Netted	0
Net Asset (Liability) on Balance Sheet	(88)
Other Current Liabilities [Member] \| Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	1,966	0
Gross Liability	(38,135)	(19,575)
Collateral Netted	5,850	8,050
Net Asset (Liability) on Balance Sheet	(30,319)	(11,525)
Other Current Liabilities [Member] \| Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	32,554	11,037
Gross Liability	(41,589)	(14,007)
Collateral Netted	6,166	487
Net Asset (Liability) on Balance Sheet	(2,869)	(2,483)
Other Current Assets [Member] \| Foreign Exchange Contract [Member]
Derivatives, Fair Value [Line Items]
Gross Asset		30
Gross Liability		0
Collateral Netted		0
Net Asset (Liability) on Balance Sheet		30
Other Current Assets [Member] \| Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	3,430	9,203
Gross Liability	(46)	(8,306)
Collateral Netted	0	0
Net Asset (Liability) on Balance Sheet	3,384	897
Other Property And Investments Net And Other Non-current Assets [Member] \| Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	1,318
Gross Liability	0
Collateral Netted	0
Net Asset (Liability) on Balance Sheet	1,318
Other Property And Investments Net And Other Non-current Assets [Member] \| Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	5,442	1,755
Gross Liability	(2,425)	(1,159)
Collateral Netted	0	0
Net Asset (Liability) on Balance Sheet	3,017	596
Other Noncurrent Liabilities [Member] \| Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Asset		952
Gross Liability		(32,190)
Collateral Netted		0
Net Asset (Liability) on Balance Sheet		(31,238)
Other Noncurrent Liabilities [Member] \| Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	78	1,725
Gross Liability	(4,504)	(8,043)
Collateral Netted	0	129
Net Asset (Liability) on Balance Sheet	$ (4,426)	$ (6,189)

Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments.

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