Consolidated Statements of Changes in Equity - Kansas City Power & Light Company Statement - USD ($) $ in Millions	Total	Common stock	Retained earnings	Derivative Hedging Instrument	AOCI - Net gains (losses) on cash flow hedges	KCP&L	KCP&L Common stock	KCP&L Retained earnings	KCP&L Derivative Hedging Instrument	KCP&L AOCI - Net gains (losses) on cash flow hedges
Beginning balance (in shares) at Dec. 31, 2017		142,094,275					1
Beginning balance at Dec. 31, 2017	$ 3,860.4	$ 2,734.8	$ 1,173.3		$ 0.0	$ 2,513.2	$ 1,563.1	$ 949.7		$ 0.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	62.9		60.5			20.2		20.2
Dividends declared on common stock	(57.7)		(57.7)			(60.0)		(60.0)
Net current period other comprehensive income	0.0					0.9			$ 0.9
Ending balance (in shares) at Mar. 31, 2018		142,233,103					1
Ending balance at Mar. 31, 2018	3,864.4	$ 2,733.6	1,176.1		0.0	2,474.3	$ 1,563.1	909.9		1.3
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		(3.0)	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)
Net current period other comprehensive income	(10.2)			$ (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		$ (13.2)	$ 2,516.7	$ 1,563.1	$ 948.6		$ 5.0