XML 50 R31.htm IDEA: XBRL DOCUMENT
v3.23.2

Benefit Plans (Tables) | 6 Months Ended
--- | ---
Jun. 30, 2023
Defined Benefit Plan Disclosure [Line Items] |
Net Periodic Benefit Costs | The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans for the three and six months ended June 30 are included below (in millions). For IPL and WPL, amounts are for their plan participants covered under plans they sponsor, as well as amounts directly assigned to them related to certain participants in the Alliant Energy and Corporate Services sponsored plans.
| Defined Benefit Pension Plans |  | OPEB Plans
| Three Months |  | Six Months |  | Three Months |  | Six Months
Alliant Energy | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022
Service cost | $1 |  | $2 |  | $2 |  | $4 |  | $— |  | $1 |  | $1 |  | $2
Interest cost | 12 |  | 9 |  | 23 |  | 18 |  | 2 |  | 2 |  | 4 |  | 3
Expected return on plan assets | (13) |  | (17) |  | (26) |  | (34) |  | (1) |  | (2) |  | (2) |  | (3)
Amortization of actuarial loss | 7 |  | 8 |  | 14 |  | 16 |  | 1 |  | — |  | 1 |  | 1
| $7 |  | $2 |  | $13 |  | $4 |  | $2 |  | $1 |  | $4 |  | $3
| Defined Benefit Pension Plans |  | OPEB Plans
| Three Months |  | Six Months |  | Three Months |  | Six Months
IPL | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022
Service cost | $1 |  | $1 |  | $2 |  | $3 |  | $— |  | $1 |  | $— |  | $1
Interest cost | 5 |  | 4 |  | 10 |  | 8 |  | 1 |  | — |  | 2 |  | 1
Expected return on plan assets | (6) |  | (8) |  | (13) |  | (16) |  | (1) |  | (1) |  | (2) |  | (2)
Amortization of actuarial loss | 3 |  | 4 |  | 6 |  | 7 |  | 1 |  | — |  | 1 |  | —
| $3 |  | $1 |  | $5 |  | $2 |  | $1 |  | $— |  | $1 |  | $—
| Defined Benefit Pension Plans |  | OPEB Plans
| Three Months |  | Six Months |  | Three Months |  | Six Months
WPL | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022
Service cost | $1 |  | $1 |  | $1 |  | $2 |  | $— |  | $— |  | $— |  | $—
Interest cost | 5 |  | 4 |  | 10 |  | 8 |  | 1 |  | — |  | 2 |  | 1
Expected return on plan assets | (6) |  | (8) |  | (11) |  | (16) |  | — |  | — |  | — |  | —
Amortization of actuarial loss | 4 |  | 4 |  | 7 |  | 8 |  | — |  | 1 |  | — |  | 1
| $4 |  | $1 |  | $7 |  | $2 |  | $1 |  | $1 |  | $2 |  | $2
Recognized Compensation Expense And Income Tax Benefits | A summary of compensation expense, including amounts allocated to IPL and WPL, and the related income tax benefits recognized for share-based compensation awards for the three and six months ended June 30 was as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| Three Months |  | Six Months |  | Three Months |  | Six Months |  | Three Months |  | Six Months
| 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022
Compensation expense | $3 |  | $3 |  | $6 |  | $7 |  | $2 |  | $1 |  | $3 |  | $4 |  | $1 |  | $1 |  | $2 |  | $3
Income tax benefits | 1 |  | 1 |  | 2 |  | 2 |  | — |  | — |  | 1 |  | 1 |  | — |  | — |  | 1 |  | 1
Schedule Of Equity-based Compensation Plans Activity | For the six months ended June 30, 2023, performance shares, performance restricted stock units and restricted stock units were granted to key employees under existing plans as follows. These shares and units will be paid out in shares of common stock, and are therefore accounted for as equity awards.
|  |  | Weighted Average
| Grants |  | Grant Date Fair Value
Performance shares | 106,927 |  | $55.68
Performance restricted stock units | 122,178 |  | 52.77
Restricted stock units | 104,849 |  | 52.81
IPL [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Net Periodic Benefit Costs | The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans for the three and six months ended June 30 are included below (in millions). For IPL and WPL, amounts are for their plan participants covered under plans they sponsor, as well as amounts directly assigned to them related to certain participants in the Alliant Energy and Corporate Services sponsored plans.
| Defined Benefit Pension Plans |  | OPEB Plans
| Three Months |  | Six Months |  | Three Months |  | Six Months
Alliant Energy | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022
Service cost | $1 |  | $2 |  | $2 |  | $4 |  | $— |  | $1 |  | $1 |  | $2
Interest cost | 12 |  | 9 |  | 23 |  | 18 |  | 2 |  | 2 |  | 4 |  | 3
Expected return on plan assets | (13) |  | (17) |  | (26) |  | (34) |  | (1) |  | (2) |  | (2) |  | (3)
Amortization of actuarial loss | 7 |  | 8 |  | 14 |  | 16 |  | 1 |  | — |  | 1 |  | 1
| $7 |  | $2 |  | $13 |  | $4 |  | $2 |  | $1 |  | $4 |  | $3
| Defined Benefit Pension Plans |  | OPEB Plans
| Three Months |  | Six Months |  | Three Months |  | Six Months
IPL | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022
Service cost | $1 |  | $1 |  | $2 |  | $3 |  | $— |  | $1 |  | $— |  | $1
Interest cost | 5 |  | 4 |  | 10 |  | 8 |  | 1 |  | — |  | 2 |  | 1
Expected return on plan assets | (6) |  | (8) |  | (13) |  | (16) |  | (1) |  | (1) |  | (2) |  | (2)
Amortization of actuarial loss | 3 |  | 4 |  | 6 |  | 7 |  | 1 |  | — |  | 1 |  | —
| $3 |  | $1 |  | $5 |  | $2 |  | $1 |  | $— |  | $1 |  | $—
| Defined Benefit Pension Plans |  | OPEB Plans
| Three Months |  | Six Months |  | Three Months |  | Six Months
WPL | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022
Service cost | $1 |  | $1 |  | $1 |  | $2 |  | $— |  | $— |  | $— |  | $—
Interest cost | 5 |  | 4 |  | 10 |  | 8 |  | 1 |  | — |  | 2 |  | 1
Expected return on plan assets | (6) |  | (8) |  | (11) |  | (16) |  | — |  | — |  | — |  | —
Amortization of actuarial loss | 4 |  | 4 |  | 7 |  | 8 |  | — |  | 1 |  | — |  | 1
| $4 |  | $1 |  | $7 |  | $2 |  | $1 |  | $1 |  | $2 |  | $2
Recognized Compensation Expense And Income Tax Benefits | A summary of compensation expense, including amounts allocated to IPL and WPL, and the related income tax benefits recognized for share-based compensation awards for the three and six months ended June 30 was as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| Three Months |  | Six Months |  | Three Months |  | Six Months |  | Three Months |  | Six Months
| 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022
Compensation expense | $3 |  | $3 |  | $6 |  | $7 |  | $2 |  | $1 |  | $3 |  | $4 |  | $1 |  | $1 |  | $2 |  | $3
Income tax benefits | 1 |  | 1 |  | 2 |  | 2 |  | — |  | — |  | 1 |  | 1 |  | — |  | — |  | 1 |  | 1
Schedule Of Equity-based Compensation Plans Activity | For the six months ended June 30, 2023, performance shares, performance restricted stock units and restricted stock units were granted to key employees under existing plans as follows. These shares and units will be paid out in shares of common stock, and are therefore accounted for as equity awards.
|  |  | Weighted Average
| Grants |  | Grant Date Fair Value
Performance shares | 106,927 |  | $55.68
Performance restricted stock units | 122,178 |  | 52.77
Restricted stock units | 104,849 |  | 52.81
WPL [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Net Periodic Benefit Costs | The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans for the three and six months ended June 30 are included below (in millions). For IPL and WPL, amounts are for their plan participants covered under plans they sponsor, as well as amounts directly assigned to them related to certain participants in the Alliant Energy and Corporate Services sponsored plans.
| Defined Benefit Pension Plans |  | OPEB Plans
| Three Months |  | Six Months |  | Three Months |  | Six Months
Alliant Energy | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022
Service cost | $1 |  | $2 |  | $2 |  | $4 |  | $— |  | $1 |  | $1 |  | $2
Interest cost | 12 |  | 9 |  | 23 |  | 18 |  | 2 |  | 2 |  | 4 |  | 3
Expected return on plan assets | (13) |  | (17) |  | (26) |  | (34) |  | (1) |  | (2) |  | (2) |  | (3)
Amortization of actuarial loss | 7 |  | 8 |  | 14 |  | 16 |  | 1 |  | — |  | 1 |  | 1
| $7 |  | $2 |  | $13 |  | $4 |  | $2 |  | $1 |  | $4 |  | $3
| Defined Benefit Pension Plans |  | OPEB Plans
| Three Months |  | Six Months |  | Three Months |  | Six Months
IPL | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022
Service cost | $1 |  | $1 |  | $2 |  | $3 |  | $— |  | $1 |  | $— |  | $1
Interest cost | 5 |  | 4 |  | 10 |  | 8 |  | 1 |  | — |  | 2 |  | 1
Expected return on plan assets | (6) |  | (8) |  | (13) |  | (16) |  | (1) |  | (1) |  | (2) |  | (2)
Amortization of actuarial loss | 3 |  | 4 |  | 6 |  | 7 |  | 1 |  | — |  | 1 |  | —
| $3 |  | $1 |  | $5 |  | $2 |  | $1 |  | $— |  | $1 |  | $—
| Defined Benefit Pension Plans |  | OPEB Plans
| Three Months |  | Six Months |  | Three Months |  | Six Months
WPL | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022
Service cost | $1 |  | $1 |  | $1 |  | $2 |  | $— |  | $— |  | $— |  | $—
Interest cost | 5 |  | 4 |  | 10 |  | 8 |  | 1 |  | — |  | 2 |  | 1
Expected return on plan assets | (6) |  | (8) |  | (11) |  | (16) |  | — |  | — |  | — |  | —
Amortization of actuarial loss | 4 |  | 4 |  | 7 |  | 8 |  | — |  | 1 |  | — |  | 1
| $4 |  | $1 |  | $7 |  | $2 |  | $1 |  | $1 |  | $2 |  | $2
Recognized Compensation Expense And Income Tax Benefits | A summary of compensation expense, including amounts allocated to IPL and WPL, and the related income tax benefits recognized for share-based compensation awards for the three and six months ended June 30 was as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| Three Months |  | Six Months |  | Three Months |  | Six Months |  | Three Months |  | Six Months
| 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022 |  | 2023 |  | 2022
Compensation expense | $3 |  | $3 |  | $6 |  | $7 |  | $2 |  | $1 |  | $3 |  | $4 |  | $1 |  | $1 |  | $2 |  | $3
Income tax benefits | 1 |  | 1 |  | 2 |  | 2 |  | — |  | — |  | 1 |  | 1 |  | — |  | — |  | 1 |  | 1
Schedule Of Equity-based Compensation Plans Activity | For the six months ended June 30, 2023, performance shares, performance restricted stock units and restricted stock units were granted to key employees under existing plans as follows. These shares and units will be paid out in shares of common stock, and are therefore accounted for as equity awards.
|  |  | Weighted Average
| Grants |  | Grant Date Fair Value
Performance shares | 106,927 |  | $55.68
Performance restricted stock units | 122,178 |  | 52.77
Restricted stock units | 104,849 |  | 52.81

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_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of share-based payment arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 1 -SubTopic 10 -Topic 718 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
Name: | us-gaap_DisclosureOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of allocation of amount expensed and capitalized for award under share-based payment arrangement to statement of income or comprehensive income and statement of financial position. Includes, but is not limited to, corresponding line item in financial statement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
Name: | us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the components of net benefit costs for pension plans and/or other employee benefit plans including service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) recognized due to settlements or curtailments. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 715 -SubTopic 20 -Subparagraph (h) -Name Accounting Standards Codification -Paragraph 1 -Section 50 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
Name: | us-gaap_ScheduleOfNetBenefitCostsTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
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: |