The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

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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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No definition available.

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Investments in Unconsolidated Affiliates (Gas Utilities and Infrastructure Investments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020
Investments In Unconsolidated Affiliates [Line Items]
Investments in equity method unconsolidated affiliates	$ 1,936	$ 1,409	$ 961
Gas Utilities and Infrastructure
Investments In Unconsolidated Affiliates [Line Items]
Investments in equity method unconsolidated affiliates	1,388	1,003	$ 215
Gas Utilities and Infrastructure \| ACP
Investments In Unconsolidated Affiliates [Line Items]
Ownership interest			47.00%
Investments in equity method unconsolidated affiliates	1,179
Gas Utilities and Infrastructure \| Sabal Trail
Investments In Unconsolidated Affiliates [Line Items]
Ownership interest			7.50%
Investments in equity method unconsolidated affiliates	121		$ 120
Gas Utilities and Infrastructure \| Other
Investments In Unconsolidated Affiliates [Line Items]
Ownership interest			29.68%
Investments in equity method unconsolidated affiliates			$ 3
Gas Utilities and Infrastructure \| Constitution
Investments In Unconsolidated Affiliates [Line Items]
Ownership interest			24.00%
Impairment losses	25	$ 55
Piedmont and Duke \| Gas Utilities and Infrastructure \| Cardinal
Investments In Unconsolidated Affiliates [Line Items]
Ownership interest			21.49%
Investments in equity method unconsolidated affiliates	9		$ 9
Piedmont and Duke \| Gas Utilities and Infrastructure \| Pine Needle
Investments In Unconsolidated Affiliates [Line Items]
Ownership interest			45.00%
Investments in equity method unconsolidated affiliates	28		$ 27
Piedmont and Duke \| Gas Utilities and Infrastructure \| Hardy Storage
Investments In Unconsolidated Affiliates [Line Items]
Ownership interest			50.00%
Investments in equity method unconsolidated affiliates	$ 51		$ 56