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v3.21.2

Retirement Plans and Postretirement Benefit Plans (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020
Defined Benefit Plan, Plan Assets, Contributions by Employer |  |  |  | $ 40.0 |
Pension Plan [Member] |  |  |  |  |
Other Comprehensive Income (Loss), Defined Benefit Plan, Adjustment for Settlement or Curtailment Gain (Loss), Tax |  | $ 0.3 | $ 0.5 | 1.9 | $ 0.6
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 2.8 | 3.3 | 8.4 | 9.8
Interest cost |  | 3.1 | 4.2 | 10.0 | 13.4
Expected return on plan assets |  | (8.5) | (9.4) | (25.6) | (28.0)
Amortization of net loss |  | 2.3 | 4.3 | 7.0 | 12.7
Defined Benefit Plan, Amortization of Prior Service Cost (Credit) |  | 0.0 | 0.0 | 0.0 | 0.0
Settlement cost |  | 3.7 | 12.1 | 35.4 | 12.1
Total net periodic benefit cost |  | 3.4 | 14.5 | 35.2 | 20.0
Amount Attributable to Unconsolidated Affiliates | [1] | (0.1) | 0.5 | (0.2) | 1.6
Net periodic benefit cost |  | 3.5 | 14.0 | 35.4 | 18.4
Capitalized portion of net periodic pension benefit cost |  | 0.9 | 0.9 | 2.5 | 2.7
Other Pension Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 0.3 | 0.2 | 0.6 | 0.6
Interest cost |  | 0.0 | 0.1 | 0.1 | 0.2
Expected return on plan assets |  | 0.0 | 0.0 | 0.0 | 0.0
Amortization of net loss |  | 0.0 | 0.1 | 0.1 | 0.4
Defined Benefit Plan, Amortization of Prior Service Cost (Credit) |  | 0.1 | 0.0 | 0.1 | 0.0
Settlement cost |  | 1.7 | 0.4 | 2.1 | 0.7
Total net periodic benefit cost |  | 2.1 | 0.8 | 3.0 | 1.9
Amount Attributable to Unconsolidated Affiliates | [1] | 0.0 | 0.1 | 0.0 | 0.1
Net periodic benefit cost |  | 2.1 | 0.7 | 3.0 | 1.8
Postretirement Benefit Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 0.1 | 0.1 | 0.2 | 0.2
Interest cost |  | 0.9 | 1.0 | 2.6 | 3.1
Expected return on plan assets |  | (0.4) | (0.5) | (1.4) | (1.4)
Amortization of net loss |  | 0.7 | 0.5 | 2.1 | 1.5
Defined Benefit Plan, Amortization of Prior Service Cost (Credit) | [2] | (1.8) | (2.1) | (5.2) | (6.3)
Total net periodic benefit cost |  | (0.5) | (1.0) | (1.7) | (2.9)
Amount Attributable to Unconsolidated Affiliates | [1] | (0.1) | (0.2) | (0.4) | (0.6)
Net periodic benefit cost |  | (0.4) | (0.8) | (1.3) | (2.3)
Capitalized portion of net periodic pension benefit cost |  | 0.1 | 0.0 | 0.2 | 0.1
OKLAHOMA | Pension Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Settlement cost | [3] | 4.4 | 10.8 | 33.3 | 11.1
Additional Pension Expense to Meet State Requirements | [3] | 3.9 | 2.4 | 11.1 | 5.7
OKLAHOMA | Postretirement Benefit Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Additional Pension Expense to Meet State Requirements | [4] | 0.1 | 0.4 | 0.3 | 1.2
ARKANSAS | Pension Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Settlement cost | [3] | 0.4 | 1.0 | 3.1 | 1.0
OG&E [Member] |  |  |  |  |
Defined Benefit Plan, Plan Assets, Contributions by Employer |  |  |  | 30.0 |
OG&E [Member] | Pension Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 2.0 | 2.3 | 5.8 | 6.8
Interest cost |  | 2.3 | 3.2 | 7.3 | 10.0
Expected return on plan assets |  | (6.2) | (7.0) | (18.5) | (20.9)
Amortization of net loss |  | 1.7 | 3.0 | 5.2 | 9.0
Settlement cost |  | 2.6 | 10.3 | 29.2 | 10.3
Total net periodic benefit cost |  | 2.4 | 11.8 | 29.0 | 15.2
Amount attributable to parent | [1] | 0.7 | 1.5 | 5.3 | 2.5
Net periodic benefit cost |  | 3.1 | 13.3 | 34.3 | 17.7
Capitalized portion of net periodic pension benefit cost |  | 0.7 | 0.8 | 2.1 | 2.3
OG&E [Member] | Other Pension Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 0.0 | 0.0 | 0.0 | 0.1
Interest cost |  | 0.0 | 0.0 | 0.0 | 0.1
Expected return on plan assets |  | 0.0 | 0.0 | 0.0 | 0.0
Amortization of net loss |  | 0.0 | 0.1 | 0.1 | 0.3
Settlement cost |  | 1.3 | 0.5 | 1.6 | 0.5
Total net periodic benefit cost |  | 1.3 | 0.6 | 1.7 | 1.0
Amount attributable to parent | [1] | 0.8 | 0.2 | 1.3 | 0.8
Net periodic benefit cost |  | 2.1 | 0.8 | 3.0 | 1.8
OG&E [Member] | Postretirement Benefit Plan [Member] |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] |  |  |  |  |
Service cost |  | 0.0 | 0.0 | 0.1 | 0.1
Interest cost |  | 0.6 | 0.8 | 1.9 | 2.4
Expected return on plan assets |  | (0.4) | (0.4) | (1.3) | (1.2)
Amortization of net loss |  | 0.6 | 0.5 | 2.0 | 1.6
Defined Benefit Plan, Amortization of Prior Service Cost (Credit) | [2] | (1.2) | (1.5) | (3.7) | (4.6)
Total net periodic benefit cost |  | (0.4) | (0.6) | (1.0) | (1.7)
Amount attributable to parent | [1] | (0.1) | (0.2) | (0.3) | (0.6)
Net periodic benefit cost |  | (0.5) | (0.8) | (1.3) | (2.3)
Capitalized portion of net periodic pension benefit cost |  | $ 0.0 | $ 0.0 | $ 0.1 | $ 0.1
[1] | "Amount paid by unconsolidated affiliates" is only applicable to OGE Energy. "Amount allocated from OGE Energy" is only applicable to OG&E.
[2] | Unamortized prior service cost is amortized on a straight-line basis over the average remaining service period to the first eligibility age of participants who are expected to receive a benefit and are active at the date of the plan amendment.
[3] | Included in the pension regulatory asset or liability in each jurisdiction, as indicated in the regulatory assets and liabilities table in Note 1.
[4] | Included in the Pension tracker, as presented in the regulatory assets and liabilities table in Note 1.

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