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Asset Retirement Obligations (Rollforward) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019
Asset Retirement Obligation [Line Items] |  |
Beginning Balance | $ 13,318 | $ 10,467
Accretion expense | 542 | 508
Liabilities settled | (724) | (895)
Liabilities incurred in the current year | 22 | 25
Revisions in estimates of cash flows | (154) | 3,213
Ending Balance | 13,004 | 13,318
Duke Energy Carolinas |  |
Asset Retirement Obligation [Line Items] |  |
Beginning Balance | 5,734 | 3,949
Accretion expense | 258 | 235
Liabilities settled | (198) | (329)
Liabilities incurred in the current year |  | 18
Revisions in estimates of cash flows | (444) | 1,861
Ending Balance | 5,350 | 5,734
Progress Energy |  |
Asset Retirement Obligation [Line Items] |  |
Beginning Balance | 6,471 | 5,411
Accretion expense | 246 | 252
Liabilities settled | (451) | (499)
Liabilities incurred in the current year | 5 | 7
Revisions in estimates of cash flows | (122) | 1,300
Ending Balance | 6,149 | 6,471
Duke Energy Progress |  |
Asset Retirement Obligation [Line Items] |  |
Beginning Balance | 5,893 | 4,820
Accretion expense | 225 | 227
Liabilities settled | (358) | (460)
Revisions in estimates of cash flows | (125) | 1,306
Ending Balance | 5,635 | 5,893
Duke Energy Florida |  |
Asset Retirement Obligation [Line Items] |  |
Beginning Balance | 578 | 591
Accretion expense | 21 | 25
Liabilities settled | (93) | (39)
Liabilities incurred in the current year | 5 | 7
Revisions in estimates of cash flows | 3 | (6)
Ending Balance | 514 | 578
Duke Energy Ohio |  |
Asset Retirement Obligation [Line Items] |  |
Beginning Balance | 80 | 93
Accretion expense | 4 | 3
Liabilities settled | (2) | (12)
Revisions in estimates of cash flows | 29 | (4)
Ending Balance | 111 | 80
Duke Energy Indiana |  |
Asset Retirement Obligation [Line Items] |  |
Beginning Balance | 832 | 722
Accretion expense | 33 | 28
Liabilities settled | (74) | (54)
Revisions in estimates of cash flows | 385 | 136
Ending Balance | 1,176 | 832
Piedmont |  |
Asset Retirement Obligation [Line Items] |  |
Beginning Balance | 17 | 19
Accretion expense | 1 | 1
Revisions in estimates of cash flows | 2 | (3)
Ending Balance | $ 20 | $ 17

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- Definition The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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- Definition Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6392676&loc=d3e7480-110848 + Details
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- Definition Amount of asset retirement obligations incurred during the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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- Definition Amount of asset retirement obligations settled, or otherwise disposed of, during the period. This may include asset retirement obligations transferred to third parties associated with the sale of a long-lived asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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- Definition Amount of increase (decrease) in the asset retirement obligation from changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 35 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=6392603&loc=d3e7123-110846 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c)(4) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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