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PENSION PLANS AND POST-RETIREMENT BENEFITS - Employee Savings Plans (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined contribution plan, cost | $ 17.4 | $ 17.6 | $ 16.3
Evergy Kansas Central |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined contribution plan, cost | 9.6 | 9.6 | 9.9
Evergy Metro |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined contribution plan, cost | $ 7.8 | $ 8.0 | $ 8.3

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- Definition Amount of cost for defined contribution plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942 + Details
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- Details
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