Pension Plans and Other Employee Benefits (Tables)

6 Months Ended

Jun. 30, 2017

Defined Benefit Plan Disclosure [Line Items]

Schedule of Net Benefit Costs [Table Text Block]

The following tables provide Great Plains Energy's components of net periodic benefit costs prior to the effects of capitalization and sharing with joint owners of power plants.

	Pension Benefits						Other Benefits
Three Months Ended June 30	2017			2016			2017			2016
Components of net periodic benefit costs	(millions)
Service cost	$	11.0		$	10.5		$	0.5		$	0.6
Interest cost	13.4			13.3			1.4			1.6
Expected return on plan assets	(12.8		)	(12.3		)	(0.7		)	(0.7		)
Prior service cost	0.2			0.1			—			0.3
Recognized net actuarial (gain)/loss	12.4			12.9			(0.1		)	(0.4		)
Net periodic benefit costs before regulatory adjustment	24.2			24.5			1.1			1.4
Regulatory adjustment	1.7			(1.0		)	0.5			1.5
Net periodic benefit costs	$	25.9		$	23.5		$	1.6		$	2.9
	Pension Benefits						Other Benefits
Year to Date June 30	2017			2016			2017			2016
Components of net periodic benefit costs	(millions)
Service cost	$	22.0		$	21.0		$	1.0		$	1.3
Interest cost	26.8			26.5			2.7			3.1
Expected return on plan assets	(25.6		)	(24.6		)	(1.3		)	(1.5		)
Prior service cost	0.4			0.3			—			0.6
Recognized net actuarial (gain)/loss	24.8			25.9			(0.2		)	(0.8		)
Net periodic benefit costs before regulatory adjustment	48.4			49.1			2.2			2.7
Regulatory adjustment	2.5			(2.0		)	1.8			3.0
Net periodic benefit costs	$	50.9		$	47.1		$	4.0		$	5.7