MERGER OF GREAT PLAINS ENERGY AND EVERGY KANSAS CENTRAL - Purchase Price Allocation (Details) $ / shares in Units, $ in Millions	Jun. 04, 2018 USD ($) $ / shares shares
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
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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