Regulatory Matters (Regulatory Matters Narrative - Piedmont) (Details) - Piedmont Natural Gas - USD ($) $ in Millions	1 Months Ended
Apr. 30, 2020	Nov. 30, 2019
Tennessee Integrity Management Rider Filing November 2018 \| TPUC
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount		$ 2
Subsequent event \| North Carolina Integrity Management Rider Filing \| NCUC
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount	$ 15

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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