Consolidated Statements of Changes in Equity - Evergy Metro, Inc - USD ($) $ in Millions	Total	Common Stock	Retained earnings	Evergy Metro	Evergy Metro Common Stock	Evergy Metro Retained earnings	Evergy Metro AOCI - Net gains (losses) on cash flow hedges
Beginning balance (in shares) at Dec. 31, 2018		255,326,252			1
Beginning balance at Dec. 31, 2018	$ 9,990.7	$ 8,685.2	$ 1,346.0	$ 2,499.8	$ 1,563.1	$ 932.6	$ 4.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	103.4		99.5	16.0		16.0
Dividends declared on common stock	(119.8)		(119.8)
Derivative hedging activity, net of tax	(10.2)			0.9			0.9
Ending balance (in shares) at Mar. 31, 2019		244,838,786			1
Ending balance at Mar. 31, 2019	9,391.7	$ 8,110.4	1,325.7	2,516.7	$ 1,563.1	948.6	5.0
Beginning balance (in shares) at Dec. 31, 2018		255,326,252			1
Beginning balance at Dec. 31, 2018	9,990.7	$ 8,685.2	1,346.0	2,499.8	$ 1,563.1	932.6	4.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	248.0			75.4
Derivative hedging activity, net of tax	(26.0)			0.8
Ending balance (in shares) at Jun. 30, 2019		235,465,848			1
Ending balance at Jun. 30, 2019	8,854.7	$ 7,563.0	1,349.1	2,511.0	$ 1,563.1	943.0	4.9
Beginning balance (in shares) at Mar. 31, 2019		244,838,786			1
Beginning balance at Mar. 31, 2019	9,391.7	$ 8,110.4	1,325.7	2,516.7	$ 1,563.1	948.6	5.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	144.6		139.7	59.4		59.4
Dividends declared on common stock	(115.8)		(115.8)	(65.0)		(65.0)
Derivative hedging activity, net of tax	(15.8)			(0.1)			(0.1)
Ending balance (in shares) at Jun. 30, 2019		235,465,848			1
Ending balance at Jun. 30, 2019	8,854.7	$ 7,563.0	1,349.1	2,511.0	$ 1,563.1	943.0	4.9
Beginning balance (in shares) at Dec. 31, 2019		226,641,443			1
Beginning balance at Dec. 31, 2019	8,545.3	$ 7,070.4	1,551.5	2,580.7	$ 1,563.1	1,012.8	4.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	72.2		69.4	25.6		25.6
Dividends declared on common stock	(114.5)		(114.5)	(60.0)		(60.0)
Derivative hedging activity, net of tax	1.3			(0.1)			(0.1)
Ending balance (in shares) at Mar. 31, 2020		226,738,748			1
Ending balance at Mar. 31, 2020	8,505.4	$ 7,072.2	1,505.7	2,546.2	$ 1,563.1	978.4	4.7
Beginning balance (in shares) at Dec. 31, 2019		226,641,443			1
Beginning balance at Dec. 31, 2019	8,545.3	$ 7,070.4	1,551.5	2,580.7	$ 1,563.1	1,012.8	4.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	208.5			128.5
Derivative hedging activity, net of tax	0.3			0.1
Ending balance (in shares) at Jun. 30, 2020		226,825,105			1
Ending balance at Jun. 30, 2020	8,526.9	$ 7,073.5	1,524.1	2,629.3	$ 1,563.1	1,061.3	4.9
Beginning balance (in shares) at Mar. 31, 2020		226,738,748			1
Beginning balance at Mar. 31, 2020	8,505.4	$ 7,072.2	1,505.7	2,546.2	$ 1,563.1	978.4	4.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	136.3		133.4	102.9		102.9
Dividends declared on common stock	(114.6)		(114.6)	(20.0)		(20.0)
Derivative hedging activity, net of tax	(1.0)			0.2			0.2
Ending balance (in shares) at Jun. 30, 2020		226,825,105			1
Ending balance at Jun. 30, 2020	$ 8,526.9	$ 7,073.5	$ 1,524.1	$ 2,629.3	$ 1,563.1	$ 1,061.3	$ 4.9