Inventory (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Fuel oil	$ 8	$ 37
Coal	83	73
Natural gas	206	22
Spare parts and finished goods	201	195
Total Inventory	498	327
Inventory [Line Items]
Inventory lower of cost or market adjustment	$ 0	29	$ 0
Fuel Oil
Inventory [Line Items]
Inventory lower of cost or market adjustment		$ 29

Inventory, Spare Parts and Finished Goods, Gross

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- Definition

Oil Inventory Lower of Cost or Market Adjustment

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- Definition

Carrying amount as of the balance sheet date of coal, which is a combustible rock or minerals which are extracted from the ground and used as fuel.

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Carrying amount as of the balance sheet date of natural gas in storage, which is a mixture of gases (liquefied or otherwise), used for fuel and manufacturing purposes, which is ready for sale.

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Carrying amount as of the balance sheet date of petroleum or crude oil.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

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