Derivative Accounting - Derivative Instruments in the Balance Sheets (Details) - USD ($)	Mar. 31, 2022	Dec. 31, 2021
Assets
Gross Recognized Derivatives	$ 297,623,000	$ 110,389,000
Liabilities
Gross Recognized Derivatives	(1,554,000)
Amount Reported on Balance Sheets	(1,706,000)	(4,373,000)
Commodity Contracts
Assets
Gross Recognized Derivatives	306,244,000	115,079,000
Amounts Offset	(8,671,000)	(4,740,000)
Net Recognized Derivatives	297,573,000	110,339,000
Other	50,000	50,000
Amount Reported on Balance Sheets	297,623,000	110,389,000
Liabilities
Gross Recognized Derivatives	(152,000)	(7,478,000)
Amounts Offset	71,000	4,740,000
Net Recognized Derivatives	(81,000)	(2,738,000)
Other	(1,625,000)	(1,635,000)
Amount Reported on Balance Sheets	(1,706,000)	(4,373,000)
Assets and Liabilities
Gross Recognized Derivatives	306,092,000	107,601,000
Amounts Offset	(8,600,000)	0
Net Recognized Derivatives	297,492,000	107,601,000
Other	(1,575,000)	(1,585,000)
Amount Reported on Balance Sheets	295,917,000	106,016,000
Cash collateral received subject to offsetting	8,600,000
Cash collateral received from counterparties	1,625,000	1,635,000
Commodity Contracts | Current assets
Assets
Gross Recognized Derivatives	214,723,000	66,777,000
Amounts Offset	(8,671,000)	(3,346,000)
Net Recognized Derivatives	206,052,000	63,431,000
Other	50,000	50,000
Amount Reported on Balance Sheets	206,102,000	63,481,000
Commodity Contracts | Investments and other assets
Assets
Gross Recognized Derivatives	91,521,000	48,302,000
Amounts Offset	0	(1,394,000)
Net Recognized Derivatives	91,521,000	46,908,000
Other	0	0
Amount Reported on Balance Sheets	91,521,000	46,908,000
Commodity Contracts | Current liabilities
Liabilities
Gross Recognized Derivatives	(152,000)	(6,084,000)
Amounts Offset	71,000	3,346,000
Net Recognized Derivatives	(81,000)	(2,738,000)
Other	(1,625,000)	(1,635,000)
Amount Reported on Balance Sheets	(1,706,000)	(4,373,000)
Assets and Liabilities
Cash collateral received from counterparties	1,625,000	1,635,000
Commodity Contracts | Deferred credits and other
Liabilities
Gross Recognized Derivatives	0	(1,394,000)
Amounts Offset	0	1,394,000
Net Recognized Derivatives	0	0
Other	0	0
Amount Reported on Balance Sheets	0	0
Assets and Liabilities
Cash collateral received from counterparties	$ 0	$ 0