MERGER OF GREAT PLAINS ENERGY AND EVERGY KANSAS CENTRAL - Schedule of Pre-tax Costs and Deferrals (Details) - Great Plains Energy $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Business Acquisition [Line Items]
One-time bill credits	$ (59.7)
Annual bill credits	(10.5)
Total impact to operating revenues	(70.2)
Charitable contributions and community support	24.7
Voluntary severance and accelerated equity compensation	47.9
Other transaction and transition costs	51.0
Reallocation and deferral of merger transition costs	(47.8)
Total impact to operating and maintenance expense	75.8
Total	(146.0)
Evergy Kansas Central
Business Acquisition [Line Items]
One-time bill credits	(23.1)
Annual bill credits	(7.9)
Total impact to operating revenues	(31.0)
Charitable contributions and community support	0.0
Voluntary severance and accelerated equity compensation	44.2
Other transaction and transition costs	21.5
Reallocation and deferral of merger transition costs	(13.8)
Total impact to operating and maintenance expense	51.9
Total	(82.9)
Evergy Metro
Business Acquisition [Line Items]
One-time bill credits	(22.4)
Annual bill credits	(2.6)
Total impact to operating revenues	(25.0)
Charitable contributions and community support	0.0
Voluntary severance and accelerated equity compensation	2.6
Other transaction and transition costs	2.1
Reallocation and deferral of merger transition costs	(23.2)
Total impact to operating and maintenance expense	(18.5)
Total	$ (6.5)