Derivative Accounting - Derivative Instruments in the Balance Sheets (Details) - USD ($)	Jun. 30, 2022	Dec. 31, 2021
Assets
Gross Recognized Derivatives	$ 248,875,000	$ 110,389,000
Liabilities
Gross Recognized Derivatives	(1,543,000)
Amount Reported on Balance Sheets	(5,596,000)	(4,373,000)
Commodity Contracts
Assets
Gross Recognized Derivatives	289,612,000	115,079,000
Amounts Offset	(40,787,000)	(4,740,000)
Net Recognized Derivatives	248,825,000	110,339,000
Other	50,000	50,000
Amount Reported on Balance Sheets	248,875,000	110,389,000
Liabilities
Gross Recognized Derivatives	(4,053,000)	(7,478,000)
Amounts Offset	357,000	4,740,000
Net Recognized Derivatives	(3,696,000)	(2,738,000)
Other	(1,900,000)	(1,635,000)
Amount Reported on Balance Sheets	(5,596,000)	(4,373,000)
Assets and Liabilities
Gross Recognized Derivatives	285,559,000	107,601,000
Amounts Offset	(40,430,000)	0
Net Recognized Derivatives	245,129,000	107,601,000
Other	(1,850,000)	(1,585,000)
Amount Reported on Balance Sheets	243,279,000	106,016,000
Cash collateral received subject to offsetting	40,430,000
Cash collateral received from counterparties	1,900,000	1,635,000
Commodity Contracts | Current assets
Assets
Gross Recognized Derivatives	177,765,000	66,777,000
Amounts Offset	(40,787,000)	(3,346,000)
Net Recognized Derivatives	136,978,000	63,431,000
Other	50,000	50,000
Amount Reported on Balance Sheets	137,028,000	63,481,000
Commodity Contracts | Investments and other assets
Assets
Gross Recognized Derivatives	111,847,000	48,302,000
Amounts Offset	0	(1,394,000)
Net Recognized Derivatives	111,847,000	46,908,000
Other	0	0
Amount Reported on Balance Sheets	$ 111,847,000	46,908,000
Commodity Contracts | Current liabilities
Liabilities
Gross Recognized Derivatives		(6,084,000)
Amounts Offset		3,346,000
Net Recognized Derivatives		(2,738,000)
Other		(1,635,000)
Amount Reported on Balance Sheets		(4,373,000)
Assets and Liabilities
Cash collateral received from counterparties		1,635,000
Commodity Contracts | Deferred credits and other
Liabilities
Gross Recognized Derivatives		(1,394,000)
Amounts Offset		1,394,000
Net Recognized Derivatives		0
Other		0
Amount Reported on Balance Sheets		0
Assets and Liabilities
Cash collateral received from counterparties		$ 0