XML 26 R7.htm IDEA: XBRL DOCUMENT
v3.23.2

Regulatory Matters | 6 Months Ended
--- | ---
Jun. 30, 2023
Public Utilities, General Disclosures [Line Items] |
Regulatory Matters | REGULATORY MATTERS Regulatory Assets and Regulatory Liabilities - Regulatory assets were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| June 30, 2023 |  | December 31, 2022 |  | June 30, 2023 |  | December 31, 2022 |  | June 30, 2023 |  | December 31, 2022
Tax-related | $957 |  | $929 |  | $868 |  | $848 |  | $89 |  | $81
Pension and OPEB costs | 378 |  | 392 |  | 190 |  | 197 |  | 188 |  | 195
Assets retired early | 290 |  | 70 |  | 274 |  | 53 |  | 16 |  | 17
Asset retirement obligations | 197 |  | 151 |  | 156 |  | 110 |  | 41 |  | 41
Commodity cost recovery | 145 |  | 160 |  | 6 |  | 1 |  | 139 |  | 159
Derivatives | 102 |  | 84 |  | 41 |  | 48 |  | 61 |  | 36
IPL’s Duane Arnold Energy Center PPA amendment | 54 |  | 66 |  | 54 |  | 66 |  | — |  | —
WPL’s Western Wisconsin gas distribution expansion investments | 47 |  | 48 |  | — |  | — |  | 47 |  | 48
Other | 174 |  | 146 |  | 59 |  | 63 |  | 115 |  | 83
| $2,344 |  | $2,046 |  | $1,648 |  | $1,386 |  | $696 |  | $660
Assets retired early - In May 2023, IPL retired the coal-fired Lansing Generating Station and reclassified the remaining net book value of this EGU from property, plant and equipment to a regulatory asset on Alliant Energy’s and IPL’s balance sheets. The related regulatory asset balance as of June 30, 2023 was $226 million, which is currently included in IPL’s rate base and IPL is earning a return of and a return on the remaining balance. Continued recovery of the remaining net book value of Lansing is expected to be addressed in future IPL rate reviews. Derivatives - Refer to Note 11 for discussion of changes in Alliant Energy’s, IPL’s and WPL’s derivative liabilities/assets during the six months ended June 30, 2023, which resulted in comparable changes to regulatory assets/liabilities on the balance sheets. Regulatory liabilities were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| June 30, 2023 |  | December 31, 2022 |  | June 30, 2023 |  | December 31, 2022 |  | June 30, 2023 |  | December 31, 2022
Tax-related | $572 |  | $579 |  | $301 |  | $303 |  | $271 |  | $276
Cost of removal obligations | 405 |  | 398 |  | 260 |  | 259 |  | 145 |  | 139
Derivatives | 90 |  | 210 |  | 48 |  | 115 |  | 42 |  | 95
Commodity cost recovery | 39 |  | 40 |  | 15 |  | 38 |  | 24 |  | 2
Electric transmission cost recovery | 19 |  | 20 |  | 14 |  | 10 |  | 5 |  | 10
WPL’s West Riverside liquidated damages | 17 |  | 32 |  | — |  | — |  | 17 |  | 32
Other | 66 |  | 45 |  | 38 |  | 29 |  | 28 |  | 16
| $1,208 |  | $1,324 |  | $676 |  | $754 |  | $532 |  | $570
WPL’s West Riverside liquidated damages - Pursuant to PSCW authorization, WPL’s amortization of liquidated damages related to West Riverside construction procurement contracts was used to offset increases in WPL’s retail electric 2022/2023 Test Period revenue requirement, which resulted in decreases in regulatory liabilities on Alliant Energy’s and WPL’s balance sheets and decreases in depreciation and amortization expenses in Alliant Energy’s and WPL’s income statements for the three and six months ended June 30, 2023.
IPL [Member] |
Public Utilities, General Disclosures [Line Items] |
Regulatory Matters | REGULATORY MATTERS Regulatory Assets and Regulatory Liabilities - Regulatory assets were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| June 30, 2023 |  | December 31, 2022 |  | June 30, 2023 |  | December 31, 2022 |  | June 30, 2023 |  | December 31, 2022
Tax-related | $957 |  | $929 |  | $868 |  | $848 |  | $89 |  | $81
Pension and OPEB costs | 378 |  | 392 |  | 190 |  | 197 |  | 188 |  | 195
Assets retired early | 290 |  | 70 |  | 274 |  | 53 |  | 16 |  | 17
Asset retirement obligations | 197 |  | 151 |  | 156 |  | 110 |  | 41 |  | 41
Commodity cost recovery | 145 |  | 160 |  | 6 |  | 1 |  | 139 |  | 159
Derivatives | 102 |  | 84 |  | 41 |  | 48 |  | 61 |  | 36
IPL’s Duane Arnold Energy Center PPA amendment | 54 |  | 66 |  | 54 |  | 66 |  | — |  | —
WPL’s Western Wisconsin gas distribution expansion investments | 47 |  | 48 |  | — |  | — |  | 47 |  | 48
Other | 174 |  | 146 |  | 59 |  | 63 |  | 115 |  | 83
| $2,344 |  | $2,046 |  | $1,648 |  | $1,386 |  | $696 |  | $660
Assets retired early - In May 2023, IPL retired the coal-fired Lansing Generating Station and reclassified the remaining net book value of this EGU from property, plant and equipment to a regulatory asset on Alliant Energy’s and IPL’s balance sheets. The related regulatory asset balance as of June 30, 2023 was $226 million, which is currently included in IPL’s rate base and IPL is earning a return of and a return on the remaining balance. Continued recovery of the remaining net book value of Lansing is expected to be addressed in future IPL rate reviews. Derivatives - Refer to Note 11 for discussion of changes in Alliant Energy’s, IPL’s and WPL’s derivative liabilities/assets during the six months ended June 30, 2023, which resulted in comparable changes to regulatory assets/liabilities on the balance sheets. Regulatory liabilities were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| June 30, 2023 |  | December 31, 2022 |  | June 30, 2023 |  | December 31, 2022 |  | June 30, 2023 |  | December 31, 2022
Tax-related | $572 |  | $579 |  | $301 |  | $303 |  | $271 |  | $276
Cost of removal obligations | 405 |  | 398 |  | 260 |  | 259 |  | 145 |  | 139
Derivatives | 90 |  | 210 |  | 48 |  | 115 |  | 42 |  | 95
Commodity cost recovery | 39 |  | 40 |  | 15 |  | 38 |  | 24 |  | 2
Electric transmission cost recovery | 19 |  | 20 |  | 14 |  | 10 |  | 5 |  | 10
WPL’s West Riverside liquidated damages | 17 |  | 32 |  | — |  | — |  | 17 |  | 32
Other | 66 |  | 45 |  | 38 |  | 29 |  | 28 |  | 16
| $1,208 |  | $1,324 |  | $676 |  | $754 |  | $532 |  | $570
WPL’s West Riverside liquidated damages - Pursuant to PSCW authorization, WPL’s amortization of liquidated damages related to West Riverside construction procurement contracts was used to offset increases in WPL’s retail electric 2022/2023 Test Period revenue requirement, which resulted in decreases in regulatory liabilities on Alliant Energy’s and WPL’s balance sheets and decreases in depreciation and amortization expenses in Alliant Energy’s and WPL’s income statements for the three and six months ended June 30, 2023.
WPL [Member] |
Public Utilities, General Disclosures [Line Items] |
Regulatory Matters | REGULATORY MATTERS Regulatory Assets and Regulatory Liabilities - Regulatory assets were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| June 30, 2023 |  | December 31, 2022 |  | June 30, 2023 |  | December 31, 2022 |  | June 30, 2023 |  | December 31, 2022
Tax-related | $957 |  | $929 |  | $868 |  | $848 |  | $89 |  | $81
Pension and OPEB costs | 378 |  | 392 |  | 190 |  | 197 |  | 188 |  | 195
Assets retired early | 290 |  | 70 |  | 274 |  | 53 |  | 16 |  | 17
Asset retirement obligations | 197 |  | 151 |  | 156 |  | 110 |  | 41 |  | 41
Commodity cost recovery | 145 |  | 160 |  | 6 |  | 1 |  | 139 |  | 159
Derivatives | 102 |  | 84 |  | 41 |  | 48 |  | 61 |  | 36
IPL’s Duane Arnold Energy Center PPA amendment | 54 |  | 66 |  | 54 |  | 66 |  | — |  | —
WPL’s Western Wisconsin gas distribution expansion investments | 47 |  | 48 |  | — |  | — |  | 47 |  | 48
Other | 174 |  | 146 |  | 59 |  | 63 |  | 115 |  | 83
| $2,344 |  | $2,046 |  | $1,648 |  | $1,386 |  | $696 |  | $660
Assets retired early - In May 2023, IPL retired the coal-fired Lansing Generating Station and reclassified the remaining net book value of this EGU from property, plant and equipment to a regulatory asset on Alliant Energy’s and IPL’s balance sheets. The related regulatory asset balance as of June 30, 2023 was $226 million, which is currently included in IPL’s rate base and IPL is earning a return of and a return on the remaining balance. Continued recovery of the remaining net book value of Lansing is expected to be addressed in future IPL rate reviews. Derivatives - Refer to Note 11 for discussion of changes in Alliant Energy’s, IPL’s and WPL’s derivative liabilities/assets during the six months ended June 30, 2023, which resulted in comparable changes to regulatory assets/liabilities on the balance sheets. Regulatory liabilities were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| June 30, 2023 |  | December 31, 2022 |  | June 30, 2023 |  | December 31, 2022 |  | June 30, 2023 |  | December 31, 2022
Tax-related | $572 |  | $579 |  | $301 |  | $303 |  | $271 |  | $276
Cost of removal obligations | 405 |  | 398 |  | 260 |  | 259 |  | 145 |  | 139
Derivatives | 90 |  | 210 |  | 48 |  | 115 |  | 42 |  | 95
Commodity cost recovery | 39 |  | 40 |  | 15 |  | 38 |  | 24 |  | 2
Electric transmission cost recovery | 19 |  | 20 |  | 14 |  | 10 |  | 5 |  | 10
WPL’s West Riverside liquidated damages | 17 |  | 32 |  | — |  | — |  | 17 |  | 32
Other | 66 |  | 45 |  | 38 |  | 29 |  | 28 |  | 16
| $1,208 |  | $1,324 |  | $676 |  | $754 |  | $532 |  | $570
WPL’s West Riverside liquidated damages - Pursuant to PSCW authorization, WPL’s amortization of liquidated damages related to West Riverside construction procurement contracts was used to offset increases in WPL’s retail electric 2022/2023 Test Period revenue requirement, which resulted in decreases in regulatory liabilities on Alliant Energy’s and WPL’s balance sheets and decreases in depreciation and amortization expenses in Alliant Energy’s and WPL’s income statements for the three and six months ended June 30, 2023.

X
- Definition The entire disclosure for public utilities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 980 -Name Accounting Standards Codification -Publisher FASB -URI https://asc.fasb.org//980/tableOfContent + Details
Name: | us-gaap_PublicUtilitiesDisclosureTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition 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. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesGeneralDisclosuresLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=lnt_IplMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=lnt_WplMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |