Fair Value Measurements Valuation Techniques for Measurement with Unobservable Inputs (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2023 USD ($) $ / MWh $ / MMBTU	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($) $ / MWh $ / MMBTU
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value measurement, sensitivity analysis, hypothetical increase or decrease of market prices, result on fair value	10.00%		10.00%
Fair Value Measurements, Sensitivity Analysis, Hypothetical Increase or Decrease of Market Prices, Result on Fair Value	$ 29,000,000		$ 37,600,000
Impairment of Intangible Assets, Finite-lived	0
Electric Portfolio [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Gain (loss) on derivatives	$ (9,100,000)	$ 38,600,000
Electric Portfolio [Member] | Discounted cash flow [Member] | Low [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Price (per MWh) | $ / MWh	50.46		55.79
Electric Portfolio [Member] | Discounted cash flow [Member] | High [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Price (per MWh) | $ / MWh	232.35		291.03
Electric Portfolio [Member] | Discounted cash flow [Member] | Weighted Average [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Price (per MWh) | $ / MWh	118.08		131.51
Electric Portfolio [Member] | Fair Value, Recurring [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative Assets	$ 135,643,000		$ 337,703,000
Derivative Liability	77,182,000		87,120,000
Electric Portfolio [Member] | Fair Value, Recurring [Member] | Level 3 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative Assets	82,391,000		119,093,000
Derivative Liability	12,657,000		3,015,000
Electric Portfolio [Member] | Fair Value, Recurring [Member] | Parent Company [Member] | Level 3 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative Assets	82,391,000		119,093,000
Derivative Liability	$ 12,657,000		$ 3,015,000
Natural Gas Portfolio [Member] | Discounted cash flow [Member] | Low [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value Inputs, Price Per Millions of BTU | $ / MMBTU	1.33		3.84
Natural Gas Portfolio [Member] | Discounted cash flow [Member] | High [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value Inputs, Price Per Millions of BTU | $ / MMBTU	7.58		7.00
Natural Gas Portfolio [Member] | Discounted cash flow [Member] | Weighted Average [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value Inputs, Price Per Millions of BTU | $ / MMBTU	3.91		4.87
Natural Gas Portfolio [Member] | Fair Value, Recurring [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative Assets	$ 54,232,000		$ 343,947,000
Derivative Liability	49,928,000		56,222,000
Natural Gas Portfolio [Member] | Fair Value, Recurring [Member] | Level 3 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative Assets	910,000		959,000
Derivative Liability	695,000		1,086,000
Natural Gas Portfolio [Member] | Fair Value, Recurring [Member] | Parent Company [Member] | Level 3 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative Assets	910,000		959,000
Derivative Liability	$ 695,000		$ 1,086,000