Consolidated Statements of Comprehensive Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
OPERATING REVENUES	$ 1,517.6	$ 1,577.6	$ 3,819.0	$ 4,016.2
OPERATING EXPENSES:
Fuel and purchased power	316.2	357.3	832.5	978.9
SPP network transmission costs	66.1	62.4	197.8	188.7
Operating and maintenance	304.6	311.6	865.5	907.1
Depreciation and amortization	218.0	216.1	658.1	645.1
Taxes other than income tax	91.0	91.5	274.2	276.4
Total Operating Expenses	995.9	1,038.9	2,828.1	2,996.2
INCOME FROM OPERATIONS	521.7	538.7	990.9	1,020.0
OTHER INCOME (EXPENSE):
Investment earnings	1.7	1.8	4.0	7.6
Other income	7.1	2.8	17.0	17.1
Other expense	(20.1)	(19.7)	(57.7)	(57.2)
Total Other Expense, Net	(11.3)	(15.1)	(36.7)	(32.5)
Interest expense	94.8	90.8	290.5	277.3
INCOME BEFORE INCOME TAXES	415.6	432.8	663.7	710.2
Income tax expense	50.0	65.5	93.8	99.2
Equity in earnings of equity method investees, net of income taxes	1.9	3.6	6.1	7.9
NET INCOME	367.5	370.9	576.0	618.9
Less: Net income attributable to noncontrolling interests	3.0	4.1	8.7	12.9
Net income attributable to Evergy, Inc.	$ 364.5	$ 366.8	$ 567.3	$ 606.0
BASIC AND DILUTED EARNINGS PER AVERAGE COMMON SHARE OUTSTANDING ATTRIBUTABLE TO EVERGY, INC. (see Note 1)
Basic earnings per common share (in dollars per share)	$ 1.60	$ 1.56	$ 2.50	$ 2.49
Diluted earnings per common share (in dollars per share)	$ 1.60	$ 1.56	$ 2.49	$ 2.49
AVERAGE COMMON SHARES OUTSTANDING
Basic (in shares)	227.3	234.6	227.2	243.5
Diluted (in shares)	227.5	235.0	227.5	243.8
COMPREHENSIVE INCOME
Net income	$ 367.5	$ 370.9	$ 576.0	$ 618.9
Derivative hedging activity
Loss on derivative hedging instruments	0.0	(29.4)	0.0	(64.4)
Income tax benefit	0.0	7.5	0.0	16.5
Net loss on derivative hedging instruments	0.0	(21.9)	0.0	(47.9)
Reclassification to expenses, net of tax	1.4	0.2	1.7	0.2
Derivative hedging activity, net of tax	1.4	(21.7)	1.7	(47.7)
Defined benefit pension plans
Amortization of net losses included in net periodic benefit costs, net of tax	0.0	0.0	(0.1)	0.0
Change in unrecognized pension expense, net of tax	0.0	0.0	(0.1)	0.0
Total other comprehensive income (loss)	1.4	(21.7)	1.6	(47.7)
COMPREHENSIVE INCOME	368.9	349.2	577.6	571.2
Less:  comprehensive income attributable to noncontrolling interest	3.0	4.1	8.7	12.9
COMPREHENSIVE INCOME	$ 365.9	$ 345.1	$ 568.9	$ 558.3