Derivative Instruments Fair Value (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 143.5	$ 82.3
Derivative Liability, Fair Value, Gross Liability	116.0	74.6
Not Designated as Hedging Instrument [Member] \| Evergy Kansas Central
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	111.9	74.9
Derivative Liability, Fair Value, Gross Liability	114.6	71.7
Not Designated as Hedging Instrument [Member] \| Evergy Metro
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	29.2	6.6
Derivative Liability, Fair Value, Gross Liability	1.0	2.3
Power commodity contract current \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	92.0	40.8
Derivative Liability, Fair Value, Gross Liability	60.7	30.8
Power commodity contract current \| Not Designated as Hedging Instrument [Member] \| Evergy Kansas Central
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	60.4	33.4
Derivative Liability, Fair Value, Gross Liability	59.3	27.9
Power commodity contract current \| Not Designated as Hedging Instrument [Member] \| Evergy Metro
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	29.2	6.6
Power commodity contract noncurrent \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	44.8	35.1
Derivative Liability, Fair Value, Gross Liability	47.8	37.0
Power commodity contract noncurrent \| Not Designated as Hedging Instrument [Member] \| Evergy Kansas Central
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	44.8	35.1
Derivative Liability, Fair Value, Gross Liability	47.8	37.0
Natural gas commodity contract noncurrent \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	0.0	0.1
Natural gas commodity contract noncurrent \| Not Designated as Hedging Instrument [Member] \| Evergy Kansas Central
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	0.0	0.1
Natural gas commodity contract current \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	6.7	6.4
Derivative Liability, Fair Value, Gross Liability	7.5	6.7
Natural gas commodity contract current \| Not Designated as Hedging Instrument [Member] \| Evergy Kansas Central
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	6.7	6.4
Derivative Liability, Fair Value, Gross Liability	7.5	6.7
Natural gas commodity contract current \| Not Designated as Hedging Instrument [Member] \| Evergy Metro
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	1.0	2.3
Commodity contract current
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	98.7	47.2
Derivative Liability, Fair Value, Gross Liability	68.2	37.5
Commodity contract current \| Evergy Kansas Central
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	67.1	39.8
Derivative Liability, Fair Value, Gross Liability	66.8	34.6
Commodity contract current \| Evergy Metro
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	29.2	6.6
Derivative Liability, Fair Value, Gross Liability	1.0	2.3
Commodity contract noncurrent
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	44.8	35.1
Derivative Liability, Fair Value, Gross Liability	47.8	37.1
Commodity contract noncurrent \| Evergy Kansas Central
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	44.8	35.1
Derivative Liability, Fair Value, Gross Liability	47.8	37.1
Commodity contract noncurrent \| Evergy Metro
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0.0	0.0
Derivative Liability, Fair Value, Gross Liability	$ 0.0	$ 0.0