Label	Element	Value
Operating Segments [Member] | Life and Health Insurance [Member]
Net Investment Income	us-gaap_NetInvestmentIncome	$ 103.9
Net Investment Income	us-gaap_NetInvestmentIncome	48.0
Net Investment Income	us-gaap_NetInvestmentIncome	53.5
Net Investment Income	us-gaap_NetInvestmentIncome	98.2
Other Income	us-gaap_OtherIncome	0.0
Other Income	us-gaap_OtherIncome	0.0
Other Income	us-gaap_OtherIncome	1.0
Other Income	us-gaap_OtherIncome	0.2
Operating Income (Loss)	us-gaap_OperatingIncomeLoss	22.2
Operating Income (Loss)	us-gaap_OperatingIncomeLoss	24.7
Operating Income (Loss)	us-gaap_OperatingIncomeLoss	47.0
Operating Income (Loss)	us-gaap_OperatingIncomeLoss	59.3
Premiums Earned, Net	us-gaap_PremiumsEarnedNet	150.7
Premiums Earned, Net	us-gaap_PremiumsEarnedNet	152.8
Premiums Earned, Net	us-gaap_PremiumsEarnedNet	294.4
Premiums Earned, Net	us-gaap_PremiumsEarnedNet	308.1
Operating Income Loss, Net Of Taxes	kmpr_OperatingIncomeLossNetOfTaxes	14.3
Operating Income Loss, Net Of Taxes	kmpr_OperatingIncomeLossNetOfTaxes	15.9
Operating Income Loss, Net Of Taxes	kmpr_OperatingIncomeLossNetOfTaxes	30.4
Operating Income Loss, Net Of Taxes	kmpr_OperatingIncomeLossNetOfTaxes	38.0
Revenues	us-gaap_Revenues	200.8
Revenues	us-gaap_Revenues	204.4
Revenues	us-gaap_Revenues	399.3
Revenues	us-gaap_Revenues	406.3
Operating Segments [Member] | Property and Casualty Insurance [Member]
Net Investment Income	us-gaap_NetInvestmentIncome	18.6
Net Investment Income	us-gaap_NetInvestmentIncome	19.5
Net Investment Income	us-gaap_NetInvestmentIncome	33.4
Net Investment Income	us-gaap_NetInvestmentIncome	37.1
Other Income	us-gaap_OtherIncome	0.1
Other Income	us-gaap_OtherIncome	0.2
Other Income	us-gaap_OtherIncome	0.3
Other Income	us-gaap_OtherIncome	0.4
Operating Income (Loss)	us-gaap_OperatingIncomeLoss	(4.3)
Operating Income (Loss)	us-gaap_OperatingIncomeLoss	(8.4)
Operating Income (Loss)	us-gaap_OperatingIncomeLoss	15.0
Operating Income (Loss)	us-gaap_OperatingIncomeLoss	9.6
Premiums Earned, Net	us-gaap_PremiumsEarnedNet	317.5
Premiums Earned, Net	us-gaap_PremiumsEarnedNet	349.4
Premiums Earned, Net	us-gaap_PremiumsEarnedNet	637.0
Premiums Earned, Net	us-gaap_PremiumsEarnedNet	639.8
Operating Income Loss, Net Of Taxes	kmpr_OperatingIncomeLossNetOfTaxes	(1.2)
Operating Income Loss, Net Of Taxes	kmpr_OperatingIncomeLossNetOfTaxes	(2.6)
Operating Income Loss, Net Of Taxes	kmpr_OperatingIncomeLossNetOfTaxes	10.8
Operating Income Loss, Net Of Taxes	kmpr_OperatingIncomeLossNetOfTaxes	13.2
Revenues	us-gaap_Revenues	337.2
Revenues	us-gaap_Revenues	368.1
Revenues	us-gaap_Revenues	670.8
Revenues	us-gaap_Revenues	$ 677.2