Derivatives and Risk Management - Schedules of Fair Values and Locations of Derivative Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Gross Asset	$ 28,520	$ 24,702
Gross Liability	(48,118)	(83,280)
Collateral Netted	6,696	8,666
Net Asset (Liability) on Balance Sheet	(12,902)	(49,912)
Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Collateral Netted	2,786	616
Other Current Liabilities [Member] \| Foreign Exchange Contract [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	0
Gross Liability	(22)
Collateral Netted	0
Net Asset (Liability) on Balance Sheet	(22)
Other Current Liabilities [Member] \| Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	0	0
Gross Liability	(10,978)	(19,575)
Collateral Netted	3,910	8,050
Net Asset (Liability) on Balance Sheet	(7,068)	(11,525)
Other Current Liabilities [Member] \| Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	17,458	11,037
Gross Liability	(21,820)	(14,007)
Collateral Netted	2,786	487
Net Asset (Liability) on Balance Sheet	(1,576)	(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] \| Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	1,743
Gross Liability	0
Collateral Netted	0
Net Asset (Liability) on Balance Sheet	1,743
Other Current Assets [Member] \| Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	749	9,203
Gross Liability	(24)	(8,306)
Collateral Netted	0	0
Net Asset (Liability) on Balance Sheet	725	897
Other Property And Investments Net And Other Non-current Assets [Member] \| Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	4,613
Gross Liability	(3,820)
Collateral Netted	0
Net Asset (Liability) on Balance Sheet	793
Other Property And Investments Net And Other Non-current Assets [Member] \| Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	2,598	1,755
Gross Liability	(1,136)	(1,159)
Collateral Netted	0	0
Net Asset (Liability) on Balance Sheet	1,462	596
Other Noncurrent Liabilities [Member] \| Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	1,264	952
Gross Liability	(5,525)	(32,190)
Collateral Netted	0	0
Net Asset (Liability) on Balance Sheet	(4,261)	(31,238)
Other Noncurrent Liabilities [Member] \| Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	95	1,725
Gross Liability	(4,793)	(8,043)
Collateral Netted	0	129
Net Asset (Liability) on Balance Sheet	$ (4,698)	$ (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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