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Regulatory Matters (Regulatory Liabilities) (Details) - USD ($) $ in Millions | Dec. 31, 2021 | Dec. 31, 2020
--- | --- | ---
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | $ 1,271 | $ 1,306
Tax-related [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 585 | 732
Cost of removal obligations [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 384 | 367
Derivatives [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 166 | 28
Electric transmission cost recovery [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 51 | 68
WPL's West Riverside liquidated damages [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 36 | 38
Other [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 49 | 73
IPL [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 691 | 676
IPL [Member] | Tax-related [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 312 | 331
IPL [Member] | Cost of removal obligations [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 252 | 238
IPL [Member] | Derivatives [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 77 | 25
IPL [Member] | Electric transmission cost recovery [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 27 | 39
IPL [Member] | Other [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 23 | 43
WPL [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 580 | 630
WPL [Member] | Tax-related [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 273 | 401
WPL [Member] | Cost of removal obligations [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 132 | 129
WPL [Member] | Derivatives [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 89 | 3
WPL [Member] | Electric transmission cost recovery [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 24 | 29
WPL [Member] | WPL's West Riverside liquidated damages [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 36 | 38
WPL [Member] | Other [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | $ 26 | $ 30

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- Definition The amount for the individual regulatory liability as itemized in a table of regulatory liabilities as of the end of the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 405 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6500807&loc=d3e48068-110394 + Details
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