MERGER OF GREAT PLAINS ENERGY AND EVERGY KANSAS CENTRAL - Purchase Price Allocation (Details) $ / shares in Units, $ in Millions		12 Months Ended
Jun. 04, 2018 USD ($) $ / shares shares	Dec. 31, 2019
Business Acquisition [Line Items]
Common stock outstanding (in shares)	215,800,074
Awards outstanding (in shares)	(204,825)
Great Plains Energy shares to be converted to Evergy shares (in shares)	215,595,249
Exchange ratio		0.5981
Great Plains Energy
Business Acquisition [Line Items]
Exchange ratio	0.5981
Number of shares issued (in shares)	128,947,518
Closing price (in dollars per share) \| $ / shares	$ 54.00
Total purchase price \| $	$ 6,975.7
Common Stock \| Great Plains Energy
Business Acquisition [Line Items]
Fair value of shares issued \| $	6,963.2
Share-based Payment Arrangement \| Great Plains Energy
Business Acquisition [Line Items]
Fair value of shares issued \| $	$ 12.5

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