Consolidated Statements of Changes in Equity - Evergy Metro, Inc - USD ($) $ in Millions	Total	Common Stock	Retained earnings	Evergy Metro Inc	Evergy Metro Inc Common Stock	Evergy Metro Inc Retained earnings	Evergy Metro Inc 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, 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