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Asset Retirement Obligations (Tables) | 9 Months Ended
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Sep. 30, 2021
Schedule of Asset Retirement Obligations [Line Items] |
Reconciliation of Changes in Asset Retirement Obligations | A reconciliation of the changes in asset retirement obligations associated with long-lived assets for the nine months ended September 30, 2021 is as follows (in millions):
| Alliant Energy |  | IPL |  |
Balance, January 1 | $251 |  | $177 |  |
Revisions in estimated cash flows | 37 |  | 32 |  |
Liabilities settled | (10) |  | (8) |  |
Liabilities incurred | 1 |  | — |  |
Accretion expense | 6 |  | 4 |  |
Balance, September 30 | $285 |  | $205 |  |
IPL [Member] |
Schedule of Asset Retirement Obligations [Line Items] |
Reconciliation of Changes in Asset Retirement Obligations | A reconciliation of the changes in asset retirement obligations associated with long-lived assets for the nine months ended September 30, 2021 is as follows (in millions):
| Alliant Energy |  | IPL |  |
Balance, January 1 | $251 |  | $177 |  |
Revisions in estimated cash flows | 37 |  | 32 |  |
Liabilities settled | (10) |  | (8) |  |
Liabilities incurred | 1 |  | — |  |
Accretion expense | 6 |  | 4 |  |
Balance, September 30 | $285 |  | $205 |  |

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- Definition Tabular disclosure of the changes in carrying amount of a liability for asset retirement obligations, for changes such as new obligations, changes in estimates of existing obligations, spending on existing obligations, property dispositions, and foreign currency translation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 30 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13201-110859 + Details
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