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FAIR VALUE MEASUREMENTS - Long-Term Debt (Details) - USD ($)
$ in Millions
Dec. 31, 2023
Dec. 31, 2022
Book Value | Fair Value, Measurements, Recurring    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-term debt $ 11,853.3 $ 10,344.8
Fair Value | Fair Value, Measurements, Recurring | Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-term debt 11,044.9 9,160.0
Evergy Kansas Central | Book Value | Fair Value, Measurements, Recurring    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-term debt 4,580.4 3,936.9
Evergy Kansas Central | Fair Value | Fair Value, Measurements, Recurring | Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-term debt 4,176.6 3,389.4
Evergy Metro | Book Value | Fair Value, Measurements, Recurring    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-term debt 2,924.4 2,926.6
Evergy Metro | Fair Value | Fair Value, Measurements, Recurring | Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-term debt 2,738.8 2,661.7
Long-Term debt fair value adjustment    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-term debt gross 87.0 92.1
Long-Term debt fair value adjustment | Evergy Kansas Central    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-term debt gross 0.0 0.0
Long-Term debt fair value adjustment | Evergy Metro    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-term debt gross $ 0.0 $ 0.0