Commitments and Contingencies Environmental Matters (Details) T in Millions, $ in Millions	6 Months Ended
	Jun. 30, 2016 USD ($) T MW	Dec. 31, 2015 USD ($)
Estimated Environmental Capital Expenditures [Abstract]
Estimate Of Environmental Capital Expenditures Current	$ 99.6
Estimate Of Environmental Capital Expenditures In Two Years	45.5
Estimate Of Environmental Capital Expenditures In Three Years	20.6
Estimate Of Environmental Capital Expenditures In Four Years	98.9
Estimate Of Environmental Capital Expenditures In Five Years	$ 151.9
Mercury and Air Toxics Standards Rule [Abstract]
Capacity of electric steam generating units that fall under MACT standards (in megawatts) | MW	25
Climate Change [Abstract]
CO2 produced per year (in millions of tons) | T	21
EPA nationwide CO2 emission reductions by 2030	32.00%
Remediation [Abstract]
Accrued environmental remediation expenses	$ 1.4	$ 1.4
MISSOURI
Climate Change [Abstract]
EPA Interim Co2 Goal Rate Reduction	26.00%
EPA Co2 Emission Reductions By 2030 By State	37.00%
KANSAS
Climate Change [Abstract]
EPA Interim Co2 Goal Rate Reduction	34.00%
EPA Co2 Emission Reductions By 2030 By State	44.00%
Kansas City Power and Light Company [Member]
Estimated Environmental Capital Expenditures [Abstract]
Estimate Of Environmental Capital Expenditures Current	$ 83.8
Estimate Of Environmental Capital Expenditures In Two Years	30.1
Estimate Of Environmental Capital Expenditures In Three Years	14.4
Estimate Of Environmental Capital Expenditures In Four Years	87.3
Estimate Of Environmental Capital Expenditures In Five Years	$ 130.0
Climate Change [Abstract]
CO2 produced per year (in millions of tons) | T	15
Remediation [Abstract]
Accrued environmental remediation expenses	$ 0.3	$ 0.3
KCPL Greater Missouri Operations [Member]
Remediation [Abstract]
Estimated amount of insurance proceeds available to cover qualified remediation expenses	$ 1.5