The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

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The current portion of money or property received from customers which is either to be returned upon satisfactory contract completion or applied to customer receivables in accordance with the terms of the contract or the understandings.

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The percentage of expected requirements covered by the aggregate notional amount of derivative contracts expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract as a percentage of expected need.

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The amount of cash or securities placed with a broker or counterparty as security for a trading or derivatives securities position which was partially obtained with funds provided by the broker dealer.

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Derivatives, Hedging Programs and Other Financial Instruments, Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Debt Instrument, Term	12 months
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ (8,000,000)
Margin Deposit Assets	0					$ 0
Customer Deposits, Current	0
Designated as Hedging Instrument \| Purchase
Derivative [Line Items]
Derivative Liability	$ 1,600,000					$ 100,000
Scenario, Forecast \| Natural Gas Member
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage			69.00%	70.00%	72.00%
Scenario, Forecast \| Electricity Member
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage			53.00%	53.00%	53.00%