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PENSION PLANS AND POST-RETIREMENT BENEFITS (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Pension Benefits |  |  |
Components of net periodic benefit costs |  |  |
Defined benefit plan, benefit obligation, beginning of the year | $ 2,718.2 | $ 2,553.4 |
Service cost | 78.9 | 79.1 | $ 60.7
Interest cost | 96.8 | 108.0 | 82.5
Contribution by participants | 0.0 | 0.0 |
Plan amendments | 4.2 |  |
Actuarial gain (loss) | 273.9 | 262.4 |
Benefits paid | (202.5) | (180.5) |
Settlements | (62.9) | 96.6 |
Other | (5.5) | (7.6) |
Defined benefit plan, benefit obligation, end of the year | 2,901.1 | 2,718.2 | 2,553.4
Change in plan assets |  |  |
Fair value of plan assets, beginning of the year | 1,732.8 | 1,603.4 |
Actual return on plan assets | 209.9 | 284.0 |
Contributions by employer and participants | 123.4 | 125.2 |
Benefits paid | (198.6) | (175.6) |
Settlements | (62.9) | (96.6) |
Other | (5.5) | (7.6) |
Fair value of plan assets, end of the year | 1,799.1 | 1,732.8 | 1,603.4
Funded status at end of year | (1,102.0) | (985.4) |
Amounts recognized in the consolidated balance sheets |  |  |
Non-current asset | 0.0 | 0.0 |
Current pension and other post-retirement liability | (4.4) | (5.6) |
Noncurrent pension liability and other post-retirement liability | (1,097.6) | (979.8) |
Net amount recognized before regulatory treatment | (1,102.0) | (985.4) |
Accumulated OCI or regulatory asset/liability | 566.9 | 454.1 |
Net amount recognized at December 31, 2020 | (535.1) | (531.3) |
Amounts in accumulated OCI or regulatory asset/liability not yet recognized as a component of net periodic benefit cost: |  |  |
Accumulated OCI or regulatory asset/liability | 566.9 | 454.1 |
Pension Benefits | Evergy Kansas Central |  |  |
Components of net periodic benefit costs |  |  |
Defined benefit plan, benefit obligation, beginning of the year | 1,323.4 | 1,258.9 |
Service cost | 27.1 | 29.0 | 32.2
Interest cost | 47.0 | 53.7 | 50.7
Contribution by participants | 0.0 | 0.0 |
Plan amendments | 8.1 |  |
Actuarial gain (loss) | 127.0 | 120.3 |
Benefits paid | (102.3) | (136.9) |
Settlements | 0.0 | 0.0 |
Other | (0.7) | (1.6) |
Defined benefit plan, benefit obligation, end of the year | 1,429.6 | 1,323.4 | 1,258.9
Change in plan assets |  |  |
Fair value of plan assets, beginning of the year | 842.1 | 804.6 |
Actual return on plan assets | 99.7 | 130.5 |
Contributions by employer and participants | 45.8 | 43.0 |
Benefits paid | (99.9) | (134.4) |
Settlements | 0.0 | 0.0 |
Other | (0.7) | (1.6) |
Fair value of plan assets, end of the year | 887.0 | 842.1 | 804.6
Funded status at end of year | (542.6) | (481.3) |
Amounts recognized in the consolidated balance sheets |  |  |
Non-current asset | 0.0 | 0.0 |
Current pension and other post-retirement liability | (2.5) | (3.0) |
Noncurrent pension liability and other post-retirement liability | (540.1) | (478.3) |
Net amount recognized before regulatory treatment | (542.6) | (481.3) |
Accumulated OCI or regulatory asset/liability | 408.0 | 354.9 |
Net amount recognized at December 31, 2020 | (134.6) | (126.4) |
Amounts in accumulated OCI or regulatory asset/liability not yet recognized as a component of net periodic benefit cost: |  |  |
Accumulated OCI or regulatory asset/liability | 408.0 | 354.9 |
Pension Benefits | Evergy Metro |  |  |
Components of net periodic benefit costs |  |  |
Defined benefit plan, benefit obligation, beginning of the year | 1,371.4 | 1,272.4 |
Service cost | 51.8 | 50.1 | 48.6
Interest cost | 49.1 | 53.3 | 49.9
Contribution by participants | 0.0 | 0.0 |
Plan amendments | (3.9) |  |
Actuarial gain (loss) | 144.8 | 140.5 |
Benefits paid | (99.0) | (42.3) |
Settlements | (62.9) | 96.6 |
Other | (4.8) | (6.0) |
Defined benefit plan, benefit obligation, end of the year | 1,446.5 | 1,371.4 | 1,272.4
Change in plan assets |  |  |
Fair value of plan assets, beginning of the year | 890.7 | 798.8 |
Actual return on plan assets | 110.2 | 153.5 |
Contributions by employer and participants | 77.6 | 82.2 |
Benefits paid | (98.7) | (41.2) |
Settlements | (62.9) | (96.6) |
Other | (4.8) | (6.0) |
Fair value of plan assets, end of the year | 912.1 | 890.7 | 798.8
Funded status at end of year | (534.4) | (480.7) |
Amounts recognized in the consolidated balance sheets |  |  |
Non-current asset | 0.0 | 0.0 |
Current pension and other post-retirement liability | (0.8) | (1.3) |
Noncurrent pension liability and other post-retirement liability | (533.6) | (479.4) |
Net amount recognized before regulatory treatment | (534.4) | (480.7) |
Accumulated OCI or regulatory asset/liability | 216.9 | 192.3 |
Net amount recognized at December 31, 2020 | (317.5) | (288.4) |
Amounts in accumulated OCI or regulatory asset/liability not yet recognized as a component of net periodic benefit cost: |  |  |
Accumulated OCI or regulatory asset/liability | 216.9 | 192.3 |
Post-Retirement Benefits |  |  |
Components of net periodic benefit costs |  |  |
Defined benefit plan, benefit obligation, beginning of the year | 264.3 | 249.3 |
Service cost | 2.7 | 2.5 | 2.3
Interest cost | 9.2 | 10.5 | 8.0
Contribution by participants | 9.3 | 8.8 |
Plan amendments | 1.0 |  |
Actuarial gain (loss) | 19.6 | 20.9 |
Benefits paid | (25.7) | (27.7) |
Settlements | 0.0 | 0.0 |
Other | 0.0 | 0.0 |
Defined benefit plan, benefit obligation, end of the year | 280.4 | 264.3 | 249.3
Change in plan assets |  |  |
Fair value of plan assets, beginning of the year | 239.9 | 223.3 |
Actual return on plan assets | 20.7 | 30.0 |
Contributions by employer and participants | 11.7 | 13.2 |
Benefits paid | (24.0) | (26.6) |
Settlements | 0.0 | 0.0 |
Other | 0.0 | 0.0 |
Fair value of plan assets, end of the year | 248.3 | 239.9 | 223.3
Funded status at end of year | (32.1) | (24.4) |
Amounts recognized in the consolidated balance sheets |  |  |
Non-current asset | 21.3 | 15.0 |
Current pension and other post-retirement liability | (1.6) | (1.9) |
Noncurrent pension liability and other post-retirement liability | (51.8) | (37.5) |
Net amount recognized before regulatory treatment | (32.1) | (24.4) |
Accumulated OCI or regulatory asset/liability | 4.0 | (4.4) |
Net amount recognized at December 31, 2020 | (28.1) | (28.8) |
Amounts in accumulated OCI or regulatory asset/liability not yet recognized as a component of net periodic benefit cost: |  |  |
Accumulated OCI or regulatory asset/liability | 4.0 | (4.4) |
Post-Retirement Benefits | Evergy Kansas Central |  |  |
Components of net periodic benefit costs |  |  |
Defined benefit plan, benefit obligation, beginning of the year | 138.7 | 133.6 |
Service cost | 1.1 | 1.1 | 1.3
Interest cost | 4.8 | 5.6 | 5.0
Contribution by participants | 1.8 | 1.9 |
Plan amendments | 0.5 |  |
Actuarial gain (loss) | 11.0 | 9.5 |
Benefits paid | (11.1) | (13.0) |
Settlements | 0.0 | 0.0 |
Other | 0.0 | 0.0 |
Defined benefit plan, benefit obligation, end of the year | 146.8 | 138.7 | 133.6
Change in plan assets |  |  |
Fair value of plan assets, beginning of the year | 120.5 | 109.7 |
Actual return on plan assets | 13.7 | 20.0 |
Contributions by employer and participants | 2.1 | 3.5 |
Benefits paid | (10.5) | (12.7) |
Settlements | 0.0 | 0.0 |
Other | 0.0 | 0.0 |
Fair value of plan assets, end of the year | 125.8 | 120.5 | 109.7
Funded status at end of year | (21.0) | (18.2) |
Amounts recognized in the consolidated balance sheets |  |  |
Non-current asset | 0.0 | 0.0 |
Current pension and other post-retirement liability | (0.8) | (1.0) |
Noncurrent pension liability and other post-retirement liability | (20.2) | (17.2) |
Net amount recognized before regulatory treatment | (21.0) | (18.2) |
Accumulated OCI or regulatory asset/liability | 1.0 | (2.9) |
Net amount recognized at December 31, 2020 | (20.0) | (21.1) |
Amounts in accumulated OCI or regulatory asset/liability not yet recognized as a component of net periodic benefit cost: |  |  |
Accumulated OCI or regulatory asset/liability | 1.0 | (2.9) |
Post-Retirement Benefits | Evergy Metro |  |  |
Components of net periodic benefit costs |  |  |
Defined benefit plan, benefit obligation, beginning of the year | 125.6 | 115.7 |
Service cost | 1.6 | 1.4 | 2.0
Interest cost | 4.4 | 4.9 | 4.8
Contribution by participants | 7.5 | 6.9 |
Plan amendments | 0.5 |  |
Actuarial gain (loss) | 8.6 | 11.4 |
Benefits paid | (14.6) | (14.7) |
Settlements | 0.0 | 0.0 |
Other | 0.0 | 0.0 |
Defined benefit plan, benefit obligation, end of the year | 133.6 | 125.6 | 115.7
Change in plan assets |  |  |
Fair value of plan assets, beginning of the year | 119.4 | 113.6 |
Actual return on plan assets | 7.0 | 10.0 |
Contributions by employer and participants | 9.6 | 9.7 |
Benefits paid | (13.5) | (13.9) |
Settlements | 0.0 | 0.0 |
Other | 0.0 | 0.0 |
Fair value of plan assets, end of the year | 122.5 | 119.4 | $ 113.6
Funded status at end of year | (11.1) | (6.2) |
Amounts recognized in the consolidated balance sheets |  |  |
Non-current asset | 21.3 | 15.0 |
Current pension and other post-retirement liability | (0.9) | (0.9) |
Noncurrent pension liability and other post-retirement liability | (31.5) | (20.3) |
Net amount recognized before regulatory treatment | (11.1) | (6.2) |
Accumulated OCI or regulatory asset/liability | (7.7) | (13.0) |
Net amount recognized at December 31, 2020 | (18.8) | (19.2) |
Amounts in accumulated OCI or regulatory asset/liability not yet recognized as a component of net periodic benefit cost: |  |  |
Accumulated OCI or regulatory asset/liability | (7.7) | (13.0) |
Actuarial (gain) loss | Pension Benefits |  |  |
Amounts in accumulated OCI or regulatory asset/liability not yet recognized as a component of net periodic benefit cost: |  |  |
Actuarial (gain) loss | 551.8 | 439.7 |
Actuarial (gain) loss | Pension Benefits | Evergy Kansas Central |  |  |
Amounts in accumulated OCI or regulatory asset/liability not yet recognized as a component of net periodic benefit cost: |  |  |
Actuarial (gain) loss | 388.9 | 342.3 |
Actuarial (gain) loss | Pension Benefits | Evergy Metro |  |  |
Amounts in accumulated OCI or regulatory asset/liability not yet recognized as a component of net periodic benefit cost: |  |  |
Actuarial (gain) loss | 218.6 | 189.4 |
Actuarial (gain) loss | Post-Retirement Benefits |  |  |
Amounts in accumulated OCI or regulatory asset/liability not yet recognized as a component of net periodic benefit cost: |  |  |
Actuarial (gain) loss | 2.2 | (5.7) |
Actuarial (gain) loss | Post-Retirement Benefits | Evergy Kansas Central |  |  |
Amounts in accumulated OCI or regulatory asset/liability not yet recognized as a component of net periodic benefit cost: |  |  |
Actuarial (gain) loss | (0.3) | (4.2) |
Actuarial (gain) loss | Post-Retirement Benefits | Evergy Metro |  |  |
Amounts in accumulated OCI or regulatory asset/liability not yet recognized as a component of net periodic benefit cost: |  |  |
Actuarial (gain) loss | 0.0 | (4.9) |
Prior service cost | Pension Benefits |  |  |
Amounts in accumulated OCI or regulatory asset/liability not yet recognized as a component of net periodic benefit cost: |  |  |
Prior service cost | 15.1 | 14.4 |
Prior service cost | Pension Benefits | Evergy Kansas Central |  |  |
Amounts in accumulated OCI or regulatory asset/liability not yet recognized as a component of net periodic benefit cost: |  |  |
Prior service cost | 19.1 | 12.6 |
Prior service cost | Pension Benefits | Evergy Metro |  |  |
Amounts in accumulated OCI or regulatory asset/liability not yet recognized as a component of net periodic benefit cost: |  |  |
Prior service cost | (1.7) | 2.9 |
Prior service cost | Post-Retirement Benefits |  |  |
Amounts in accumulated OCI or regulatory asset/liability not yet recognized as a component of net periodic benefit cost: |  |  |
Prior service cost | 1.8 | 1.3 |
Prior service cost | Post-Retirement Benefits | Evergy Kansas Central |  |  |
Amounts in accumulated OCI or regulatory asset/liability not yet recognized as a component of net periodic benefit cost: |  |  |
Prior service cost | 1.3 | 1.3 |
Prior service cost | Post-Retirement Benefits | Evergy Metro |  |  |
Amounts in accumulated OCI or regulatory asset/liability not yet recognized as a component of net periodic benefit cost: |  |  |
Prior service cost | $ (7.7) | $ (8.1) |

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- Definition Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109237824&loc=d3e1703-114919 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 + Details
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- Definition Amount of cost recognized for passage of time related to defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(2) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 3A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109237824&loc=SL108413299-114919 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4587-114921 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920 + Details
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- Definition Amount of increase (decrease) in benefit obligation of defined benefit plan from change in terms of existing plan or initiation of new plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(7) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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- Definition Amount of payment to participant under defined benefit plan which decreases plan assets. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(5) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 60 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6414203&loc=d3e39716-114964 + Details
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