XML 50 R30.htm IDEA: XBRL DOCUMENT v3.25.3
Benefit Plans (Tables)
 9 Months Ended
Sep. 30, 2025
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 nine months ended September 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 PlansOPEB Plans
Three MonthsNine MonthsThree MonthsNine Months
Alliant Energy20252024202520242025202420252024
Service cost$1$1$3$3$—$1$1$2
Interest cost111234342266
Expected return on plan assets(13)(14)(40)(41)—(2)(3)(4)
Amortization of prior service credit(1)—(1)—————
Amortization of actuarial loss661718————
$4$5$13$14$2$1$4$4
Defined Benefit Pension PlansOPEB Plans
Three MonthsNine MonthsThree MonthsNine Months
IPL20252024202520242025202420252024
Service cost$1$1$2$2$—$—$—$—
Interest cost551515—123
Expected return on plan assets(7)(7)(19)(20)(1)(1)(3)(3)
Amortization of actuarial loss3277————
$2$1$5$4($1)$—($1)$—
Defined Benefit Pension PlansOPEB Plans
Three MonthsNine MonthsThree MonthsNine Months
WPL20252024202520242025202420252024
Service cost$—$—$1$1$—$—$—$—
Interest cost5515151123
Expected return on plan assets(5)(6)(17)(18)(1)(1)(1)(1)
Amortization of actuarial loss3389————
$3$2$7$7$—$—$1$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 nine months ended September 30 was as follows (in millions):
Alliant EnergyIPLWPL
Three MonthsNine Months Three MonthsNine Months Three MonthsNine Months
202520242025202420252024202520242025202420252024
Compensation expense$6$3$13$10$3$2$7$5$2$1$6$4
Income tax benefits21431—211—21
Schedule Of Equity-based Compensation Plans Activity
For the nine months ended September 30, 2025, performance shares and restricted stock units were granted to key employees under the equity-based compensation 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
GrantsGrant Date Fair Value
Performance shares (total shareowner return metric)105,896$66.52
Performance shares (net income and environmental metrics)118,88361.63
Restricted stock units100,24561.66
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 nine months ended September 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 PlansOPEB Plans
Three MonthsNine MonthsThree MonthsNine Months
Alliant Energy20252024202520242025202420252024
Service cost$1$1$3$3$—$1$1$2
Interest cost111234342266
Expected return on plan assets(13)(14)(40)(41)—(2)(3)(4)
Amortization of prior service credit(1)—(1)—————
Amortization of actuarial loss661718————
$4$5$13$14$2$1$4$4
Defined Benefit Pension PlansOPEB Plans
Three MonthsNine MonthsThree MonthsNine Months
IPL20252024202520242025202420252024
Service cost$1$1$2$2$—$—$—$—
Interest cost551515—123
Expected return on plan assets(7)(7)(19)(20)(1)(1)(3)(3)
Amortization of actuarial loss3277————
$2$1$5$4($1)$—($1)$—
Defined Benefit Pension PlansOPEB Plans
Three MonthsNine MonthsThree MonthsNine Months
WPL20252024202520242025202420252024
Service cost$—$—$1$1$—$—$—$—
Interest cost5515151123
Expected return on plan assets(5)(6)(17)(18)(1)(1)(1)(1)
Amortization of actuarial loss3389————
$3$2$7$7$—$—$1$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 nine months ended September 30 was as follows (in millions):
Alliant EnergyIPLWPL
Three MonthsNine Months Three MonthsNine Months Three MonthsNine Months
202520242025202420252024202520242025202420252024
Compensation expense$6$3$13$10$3$2$7$5$2$1$6$4
Income tax benefits21431—211—21
Schedule Of Equity-based Compensation Plans Activity
For the nine months ended September 30, 2025, performance shares and restricted stock units were granted to key employees under the equity-based compensation 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
GrantsGrant Date Fair Value
Performance shares (total shareowner return metric)105,896$66.52
Performance shares (net income and environmental metrics)118,88361.63
Restricted stock units100,24561.66
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 nine months ended September 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 PlansOPEB Plans
Three MonthsNine MonthsThree MonthsNine Months
Alliant Energy20252024202520242025202420252024
Service cost$1$1$3$3$—$1$1$2
Interest cost111234342266
Expected return on plan assets(13)(14)(40)(41)—(2)(3)(4)
Amortization of prior service credit(1)—(1)—————
Amortization of actuarial loss661718————
$4$5$13$14$2$1$4$4
Defined Benefit Pension PlansOPEB Plans
Three MonthsNine MonthsThree MonthsNine Months
IPL20252024202520242025202420252024
Service cost$1$1$2$2$—$—$—$—
Interest cost551515—123
Expected return on plan assets(7)(7)(19)(20)(1)(1)(3)(3)
Amortization of actuarial loss3277————
$2$1$5$4($1)$—($1)$—
Defined Benefit Pension PlansOPEB Plans
Three MonthsNine MonthsThree MonthsNine Months
WPL20252024202520242025202420252024
Service cost$—$—$1$1$—$—$—$—
Interest cost5515151123
Expected return on plan assets(5)(6)(17)(18)(1)(1)(1)(1)
Amortization of actuarial loss3389————
$3$2$7$7$—$—$1$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 nine months ended September 30 was as follows (in millions):
Alliant EnergyIPLWPL
Three MonthsNine Months Three MonthsNine Months Three MonthsNine Months
202520242025202420252024202520242025202420252024
Compensation expense$6$3$13$10$3$2$7$5$2$1$6$4
Income tax benefits21431—211—21
Schedule Of Equity-based Compensation Plans Activity
For the nine months ended September 30, 2025, performance shares and restricted stock units were granted to key employees under the equity-based compensation 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
GrantsGrant Date Fair Value
Performance shares (total shareowner return metric)105,896$66.52
Performance shares (net income and environmental metrics)118,88361.63
Restricted stock units100,24561.66