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Fair Value Measurements (Reconciliation of Assets and Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs) (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019
Derivatives (net) |  |  |  |
Balance at beginning of period | $ (92) | $ (79) | $ (102) | $ (113)
Total pretax realized or unrealized gains included in comprehensive income | (102) |  | (102) |
Purchases, sales, issuances and settlements: |  |  |  |
Purchases |  |  | 14 | 38
Settlements | (3) | (9) | (18) | (32)
Total (losses) gains included on the Condensed Consolidated Balance Sheet | (6) | (2) | 5 | 17
Balance at end of period | (203) | (90) | (203) | (90)
Duke Energy Indiana |  |  |  |
Derivatives (net) |  |  |  |
Balance at beginning of period | 10 | 28 | 11 | 22
Purchases, sales, issuances and settlements: |  |  |  |
Purchases |  |  | 10 | 29
Settlements | (3) | (7) | (13) | (26)
Total (losses) gains included on the Condensed Consolidated Balance Sheet | 1 | (5) | 0 | (9)
Balance at end of period | 8 | 16 | 8 | 16
Piedmont Natural Gas |  |  |  |
Derivatives (net) |  |  |  |
Balance at beginning of period | (105) | (114) | (117) | (141)
Purchases, sales, issuances and settlements: |  |  |  |
Total (losses) gains and settlements | (6) | 3 | 6 | 30
Balance at end of period | $ (111) | $ (111) | $ (111) | $ (111)

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- Definition Total amount, including deferred gains or losses, recorded as regulatory assets and liabilities [net] measured at fair value on a recurring basis using unobservable inputs (Level 3) which have taken place during the period. + References No definition available. + Details
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- Definition Amount of gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1a) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
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- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
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- Definition Amount of increase (decrease) of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19279-110258 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
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- Definition Amount of purchases of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19279-110258 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
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- Definition Amount of settlements of financial instrument classified as a derivative asset (liability) after deduction of derivative liability, measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19279-110258 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
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