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Benefit Plans | 6 Months Ended
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Jun. 30, 2019
Benefit Plans | BENEFIT PLANS NOTE 10(a) Pension and OPEB Plans - 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 represent their current and former employees covered under plans they sponsor, as well as amounts directly assigned to them related to their current and former employees who are 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 | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018
Service cost |  | $2.4 |  |  |  | $3.0 |  |  |  | $4.8 |  |  |  | $6.0 |  |  |  | $0.9 |  |  |  | $1.0 |  |  |  | $1.7 |  |  |  | $2.1 |
Interest cost | 12.4 |  |  | 11.7 |  |  | 24.9 |  |  | 23.4 |  |  | 2.1 |  |  | 1.9 |  |  | 4.2 |  |  | 3.8 |
Expected return on plan assets | (15.0 | ) |  | (17.5 | ) |  | (30.0 | ) |  | (34.9 | ) |  | (1.3 | ) |  | (1.5 | ) |  | (2.5 | ) |  | (3.0 | )
Amortization of prior service credit | (0.1 | ) |  | (0.1 | ) |  | (0.3 | ) |  | (0.3 | ) |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | )
Amortization of actuarial loss | 9.1 |  |  | 8.8 |  |  | 18.2 |  |  | 17.6 |  |  | 0.8 |  |  | 0.9 |  |  | 1.6 |  |  | 1.7 |
|  | $8.8 |  |  |  | $5.9 |  |  |  | $17.6 |  |  |  | $11.8 |  |  |  | $2.4 |  |  |  | $2.2 |  |  |  | $4.9 |  |  |  | $4.5 |
| Defined Benefit Pension Plans |  | OPEB Plans
| Three Months |  | Six Months |  | Three Months |  | Six Months
IPL | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018
Service cost |  | $1.5 |  |  |  | $1.9 |  |  |  | $3.0 |  |  |  | $3.7 |  |  |  | $0.4 |  |  |  | $0.5 |  |  |  | $0.7 |  |  |  | $0.9 |
Interest cost | 5.7 |  |  | 5.4 |  |  | 11.4 |  |  | 10.7 |  |  | 0.9 |  |  | 0.8 |  |  | 1.7 |  |  | 1.6 |
Expected return on plan assets | (7.1 | ) |  | (8.2 | ) |  | (14.1 | ) |  | (16.3 | ) |  | (0.9 | ) |  | (1.1 | ) |  | (1.8 | ) |  | (2.2 | )
Amortization of prior service credit | — |  |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | ) |  | — |  |  | — |  |  | — |  |  | — |
Amortization of actuarial loss | 4.0 |  |  | 3.8 |  |  | 7.9 |  |  | 7.5 |  |  | 0.3 |  |  | 0.3 |  |  | 0.7 |  |  | 0.6 |
|  | $4.1 |  |  |  | $2.8 |  |  |  | $8.1 |  |  |  | $5.5 |  |  |  | $0.7 |  |  |  | $0.5 |  |  |  | $1.3 |  |  |  | $0.9 |
| Defined Benefit Pension Plans |  | OPEB Plans
| Three Months |  | Six Months |  | Three Months |  | Six Months
WPL | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018
Service cost |  | $0.8 |  |  |  | $1.1 |  |  |  | $1.7 |  |  |  | $2.2 |  |  |  | $0.3 |  |  |  | $0.4 |  |  |  | $0.6 |  |  |  | $0.8 |
Interest cost | 5.4 |  |  | 5.1 |  |  | 10.8 |  |  | 10.1 |  |  | 0.9 |  |  | 0.7 |  |  | 1.7 |  |  | 1.5 |
Expected return on plan assets | (6.6 | ) |  | (7.6 | ) |  | (13.1 | ) |  | (15.2 | ) |  | (0.2 | ) |  | (0.1 | ) |  | (0.3 | ) |  | (0.3 | )
Amortization of prior service credit | — |  |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | )
Amortization of actuarial loss | 4.4 |  |  | 4.3 |  |  | 8.8 |  |  | 8.6 |  |  | 0.4 |  |  | 0.5 |  |  | 0.8 |  |  | 1.0 |
|  | $4.0 |  |  |  | $2.8 |  |  |  | $8.1 |  |  |  | $5.6 |  |  |  | $1.3 |  |  |  | $1.4 |  |  |  | $2.7 |  |  |  | $2.9 |
NOTE 10(b) Equity-based Compensation Plans - 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
| 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018
Compensation expense |  | $3.4 |  |  |  | $5.1 |  |  |  | $8.1 |  |  |  | $8.4 |  |  |  | $1.9 |  |  |  | $2.8 |  |  |  | $4.5 |  |  |  | $4.6 |  |  |  | $1.4 |  |  |  | $2.1 |  |  |  | $3.2 |  |  |  | $3.4 |
Income tax benefits | 1.0 |  |  | 1.5 |  |  | 2.3 |  |  | 2.4 |  |  | 0.5 |  |  | 0.9 |  |  | 1.3 |  |  | 1.4 |  |  | 0.4 |  |  | 0.5 |  |  | 0.9 |  |  | 0.9 |
As of June 30, 2019, Alliant Energy’s, IPL’s and WPL’s total unrecognized compensation cost related to share-based compensation awards was $10.3 million, $5.7 million and $4.2 million, respectively, which is expected to be recognized over a weighted average period of between 1 and 2 years. In the first quarter of 2019, performance shares, performance restricted stock units and restricted stock units were granted to key employees and will be paid out in shares, and are therefore accounted for as equity awards. The 2019 performance shares contain a market condition based on total shareowner return relative to an investor-owned utility peer group. The fair value of each performance share is based on the fair value of the underlying common stock on the grant date and the probability of satisfying the market condition contained in the agreement during a 3-year performance period. In the first quarter of 2019, 80,837 performance shares were granted with a grant date fair value of $46.35. The 2019 performance restricted stock units will vest based on the achievement of certain targets (specified growth of consolidated net income from continuing operations) during a 3-year performance period. The actual number of performance shares and performance restricted units that will be paid out upon vesting is dependent upon actual performance and may range from zero to 200% of the target number of shares or units, as applicable. The 2019 restricted stock units will vest based on the expiration of a 3- year time-vesting period. In the first quarter of 2019, 80,837 performance restricted stock units and 95,938 restricted stock units were granted with a grant date fair value of $45.63, which is based on the closing market price of one share of Alliant Energy’s common stock on the grant date of the award. As of June 30, 2019, an immaterial amount of shares was included in the calculation of diluted EPS related to the nonvested equity awards.
IPL [Member] |
Benefit Plans | BENEFIT PLANS NOTE 10(a) Pension and OPEB Plans - 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 represent their current and former employees covered under plans they sponsor, as well as amounts directly assigned to them related to their current and former employees who are 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 | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018
Service cost |  | $2.4 |  |  |  | $3.0 |  |  |  | $4.8 |  |  |  | $6.0 |  |  |  | $0.9 |  |  |  | $1.0 |  |  |  | $1.7 |  |  |  | $2.1 |
Interest cost | 12.4 |  |  | 11.7 |  |  | 24.9 |  |  | 23.4 |  |  | 2.1 |  |  | 1.9 |  |  | 4.2 |  |  | 3.8 |
Expected return on plan assets | (15.0 | ) |  | (17.5 | ) |  | (30.0 | ) |  | (34.9 | ) |  | (1.3 | ) |  | (1.5 | ) |  | (2.5 | ) |  | (3.0 | )
Amortization of prior service credit | (0.1 | ) |  | (0.1 | ) |  | (0.3 | ) |  | (0.3 | ) |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | )
Amortization of actuarial loss | 9.1 |  |  | 8.8 |  |  | 18.2 |  |  | 17.6 |  |  | 0.8 |  |  | 0.9 |  |  | 1.6 |  |  | 1.7 |
|  | $8.8 |  |  |  | $5.9 |  |  |  | $17.6 |  |  |  | $11.8 |  |  |  | $2.4 |  |  |  | $2.2 |  |  |  | $4.9 |  |  |  | $4.5 |
| Defined Benefit Pension Plans |  | OPEB Plans
| Three Months |  | Six Months |  | Three Months |  | Six Months
IPL | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018
Service cost |  | $1.5 |  |  |  | $1.9 |  |  |  | $3.0 |  |  |  | $3.7 |  |  |  | $0.4 |  |  |  | $0.5 |  |  |  | $0.7 |  |  |  | $0.9 |
Interest cost | 5.7 |  |  | 5.4 |  |  | 11.4 |  |  | 10.7 |  |  | 0.9 |  |  | 0.8 |  |  | 1.7 |  |  | 1.6 |
Expected return on plan assets | (7.1 | ) |  | (8.2 | ) |  | (14.1 | ) |  | (16.3 | ) |  | (0.9 | ) |  | (1.1 | ) |  | (1.8 | ) |  | (2.2 | )
Amortization of prior service credit | — |  |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | ) |  | — |  |  | — |  |  | — |  |  | — |
Amortization of actuarial loss | 4.0 |  |  | 3.8 |  |  | 7.9 |  |  | 7.5 |  |  | 0.3 |  |  | 0.3 |  |  | 0.7 |  |  | 0.6 |
|  | $4.1 |  |  |  | $2.8 |  |  |  | $8.1 |  |  |  | $5.5 |  |  |  | $0.7 |  |  |  | $0.5 |  |  |  | $1.3 |  |  |  | $0.9 |
| Defined Benefit Pension Plans |  | OPEB Plans
| Three Months |  | Six Months |  | Three Months |  | Six Months
WPL | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018
Service cost |  | $0.8 |  |  |  | $1.1 |  |  |  | $1.7 |  |  |  | $2.2 |  |  |  | $0.3 |  |  |  | $0.4 |  |  |  | $0.6 |  |  |  | $0.8 |
Interest cost | 5.4 |  |  | 5.1 |  |  | 10.8 |  |  | 10.1 |  |  | 0.9 |  |  | 0.7 |  |  | 1.7 |  |  | 1.5 |
Expected return on plan assets | (6.6 | ) |  | (7.6 | ) |  | (13.1 | ) |  | (15.2 | ) |  | (0.2 | ) |  | (0.1 | ) |  | (0.3 | ) |  | (0.3 | )
Amortization of prior service credit | — |  |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | )
Amortization of actuarial loss | 4.4 |  |  | 4.3 |  |  | 8.8 |  |  | 8.6 |  |  | 0.4 |  |  | 0.5 |  |  | 0.8 |  |  | 1.0 |
|  | $4.0 |  |  |  | $2.8 |  |  |  | $8.1 |  |  |  | $5.6 |  |  |  | $1.3 |  |  |  | $1.4 |  |  |  | $2.7 |  |  |  | $2.9 |
NOTE 10(b) Equity-based Compensation Plans - 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
| 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018
Compensation expense |  | $3.4 |  |  |  | $5.1 |  |  |  | $8.1 |  |  |  | $8.4 |  |  |  | $1.9 |  |  |  | $2.8 |  |  |  | $4.5 |  |  |  | $4.6 |  |  |  | $1.4 |  |  |  | $2.1 |  |  |  | $3.2 |  |  |  | $3.4 |
Income tax benefits | 1.0 |  |  | 1.5 |  |  | 2.3 |  |  | 2.4 |  |  | 0.5 |  |  | 0.9 |  |  | 1.3 |  |  | 1.4 |  |  | 0.4 |  |  | 0.5 |  |  | 0.9 |  |  | 0.9 |
As of June 30, 2019, Alliant Energy’s, IPL’s and WPL’s total unrecognized compensation cost related to share-based compensation awards was $10.3 million, $5.7 million and $4.2 million, respectively, which is expected to be recognized over a weighted average period of between 1 and 2 years. In the first quarter of 2019, performance shares, performance restricted stock units and restricted stock units were granted to key employees and will be paid out in shares, and are therefore accounted for as equity awards. The 2019 performance shares contain a market condition based on total shareowner return relative to an investor-owned utility peer group. The fair value of each performance share is based on the fair value of the underlying common stock on the grant date and the probability of satisfying the market condition contained in the agreement during a 3-year performance period. In the first quarter of 2019, 80,837 performance shares were granted with a grant date fair value of $46.35. The 2019 performance restricted stock units will vest based on the achievement of certain targets (specified growth of consolidated net income from continuing operations) during a 3-year performance period. The actual number of performance shares and performance restricted units that will be paid out upon vesting is dependent upon actual performance and may range from zero to 200% of the target number of shares or units, as applicable. The 2019 restricted stock units will vest based on the expiration of a 3- year time-vesting period. In the first quarter of 2019, 80,837 performance restricted stock units and 95,938 restricted stock units were granted with a grant date fair value of $45.63, which is based on the closing market price of one share of Alliant Energy’s common stock on the grant date of the award. As of June 30, 2019, an immaterial amount of shares was included in the calculation of diluted EPS related to the nonvested equity awards.
WPL [Member] |
Benefit Plans | BENEFIT PLANS NOTE 10(a) Pension and OPEB Plans - 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 represent their current and former employees covered under plans they sponsor, as well as amounts directly assigned to them related to their current and former employees who are 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 | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018
Service cost |  | $2.4 |  |  |  | $3.0 |  |  |  | $4.8 |  |  |  | $6.0 |  |  |  | $0.9 |  |  |  | $1.0 |  |  |  | $1.7 |  |  |  | $2.1 |
Interest cost | 12.4 |  |  | 11.7 |  |  | 24.9 |  |  | 23.4 |  |  | 2.1 |  |  | 1.9 |  |  | 4.2 |  |  | 3.8 |
Expected return on plan assets | (15.0 | ) |  | (17.5 | ) |  | (30.0 | ) |  | (34.9 | ) |  | (1.3 | ) |  | (1.5 | ) |  | (2.5 | ) |  | (3.0 | )
Amortization of prior service credit | (0.1 | ) |  | (0.1 | ) |  | (0.3 | ) |  | (0.3 | ) |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | )
Amortization of actuarial loss | 9.1 |  |  | 8.8 |  |  | 18.2 |  |  | 17.6 |  |  | 0.8 |  |  | 0.9 |  |  | 1.6 |  |  | 1.7 |
|  | $8.8 |  |  |  | $5.9 |  |  |  | $17.6 |  |  |  | $11.8 |  |  |  | $2.4 |  |  |  | $2.2 |  |  |  | $4.9 |  |  |  | $4.5 |
| Defined Benefit Pension Plans |  | OPEB Plans
| Three Months |  | Six Months |  | Three Months |  | Six Months
IPL | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018
Service cost |  | $1.5 |  |  |  | $1.9 |  |  |  | $3.0 |  |  |  | $3.7 |  |  |  | $0.4 |  |  |  | $0.5 |  |  |  | $0.7 |  |  |  | $0.9 |
Interest cost | 5.7 |  |  | 5.4 |  |  | 11.4 |  |  | 10.7 |  |  | 0.9 |  |  | 0.8 |  |  | 1.7 |  |  | 1.6 |
Expected return on plan assets | (7.1 | ) |  | (8.2 | ) |  | (14.1 | ) |  | (16.3 | ) |  | (0.9 | ) |  | (1.1 | ) |  | (1.8 | ) |  | (2.2 | )
Amortization of prior service credit | — |  |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | ) |  | — |  |  | — |  |  | — |  |  | — |
Amortization of actuarial loss | 4.0 |  |  | 3.8 |  |  | 7.9 |  |  | 7.5 |  |  | 0.3 |  |  | 0.3 |  |  | 0.7 |  |  | 0.6 |
|  | $4.1 |  |  |  | $2.8 |  |  |  | $8.1 |  |  |  | $5.5 |  |  |  | $0.7 |  |  |  | $0.5 |  |  |  | $1.3 |  |  |  | $0.9 |
| Defined Benefit Pension Plans |  | OPEB Plans
| Three Months |  | Six Months |  | Three Months |  | Six Months
WPL | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018
Service cost |  | $0.8 |  |  |  | $1.1 |  |  |  | $1.7 |  |  |  | $2.2 |  |  |  | $0.3 |  |  |  | $0.4 |  |  |  | $0.6 |  |  |  | $0.8 |
Interest cost | 5.4 |  |  | 5.1 |  |  | 10.8 |  |  | 10.1 |  |  | 0.9 |  |  | 0.7 |  |  | 1.7 |  |  | 1.5 |
Expected return on plan assets | (6.6 | ) |  | (7.6 | ) |  | (13.1 | ) |  | (15.2 | ) |  | (0.2 | ) |  | (0.1 | ) |  | (0.3 | ) |  | (0.3 | )
Amortization of prior service credit | — |  |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | ) |  | (0.1 | )
Amortization of actuarial loss | 4.4 |  |  | 4.3 |  |  | 8.8 |  |  | 8.6 |  |  | 0.4 |  |  | 0.5 |  |  | 0.8 |  |  | 1.0 |
|  | $4.0 |  |  |  | $2.8 |  |  |  | $8.1 |  |  |  | $5.6 |  |  |  | $1.3 |  |  |  | $1.4 |  |  |  | $2.7 |  |  |  | $2.9 |
NOTE 10(b) Equity-based Compensation Plans - 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
| 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018 |  | 2019 |  | 2018
Compensation expense |  | $3.4 |  |  |  | $5.1 |  |  |  | $8.1 |  |  |  | $8.4 |  |  |  | $1.9 |  |  |  | $2.8 |  |  |  | $4.5 |  |  |  | $4.6 |  |  |  | $1.4 |  |  |  | $2.1 |  |  |  | $3.2 |  |  |  | $3.4 |
Income tax benefits | 1.0 |  |  | 1.5 |  |  | 2.3 |  |  | 2.4 |  |  | 0.5 |  |  | 0.9 |  |  | 1.3 |  |  | 1.4 |  |  | 0.4 |  |  | 0.5 |  |  | 0.9 |  |  | 0.9 |
As of June 30, 2019, Alliant Energy’s, IPL’s and WPL’s total unrecognized compensation cost related to share-based compensation awards was $10.3 million, $5.7 million and $4.2 million, respectively, which is expected to be recognized over a weighted average period of between 1 and 2 years. In the first quarter of 2019, performance shares, performance restricted stock units and restricted stock units were granted to key employees and will be paid out in shares, and are therefore accounted for as equity awards. The 2019 performance shares contain a market condition based on total shareowner return relative to an investor-owned utility peer group. The fair value of each performance share is based on the fair value of the underlying common stock on the grant date and the probability of satisfying the market condition contained in the agreement during a 3-year performance period. In the first quarter of 2019, 80,837 performance shares were granted with a grant date fair value of $46.35. The 2019 performance restricted stock units will vest based on the achievement of certain targets (specified growth of consolidated net income from continuing operations) during a 3-year performance period. The actual number of performance shares and performance restricted units that will be paid out upon vesting is dependent upon actual performance and may range from zero to 200% of the target number of shares or units, as applicable. The 2019 restricted stock units will vest based on the expiration of a 3- year time-vesting period. In the first quarter of 2019, 80,837 performance restricted stock units and 95,938 restricted stock units were granted with a grant date fair value of $45.63, which is based on the closing market price of one share of Alliant Energy’s common stock on the grant date of the award. As of June 30, 2019, an immaterial amount of shares was included in the calculation of diluted EPS related to the nonvested equity awards.

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- Definition The entire disclosure for an entity's employee compensation and benefit plans, including, but not limited to, postemployment and postretirement benefit plans, defined benefit pension plans, defined contribution plans, non-qualified and supplemental benefit plans, deferred compensation, share-based compensation, life insurance, severance, health care, unemployment and other benefit plans. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -URI http://asc.fasb.org/topic&trid=2228938 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 712 -URI http://asc.fasb.org/topic&trid=2197446 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 710 -URI http://asc.fasb.org/topic&trid=2127225 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -URI http://asc.fasb.org/topic&trid=2235017 + Details
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