Related Parties (Details) (FS&C [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transaction [Line Items]
Related Party Transaction Amount of Assets in Defined Contributions Plans		$ 22.8	$ 20.4
Related Party Transaction Percent of Assets in Defined Contribution Plan Assets		6.00%	7.00%
Trinity [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Amounts of Assets Managed by Investment Advisory Firm under Director's Management	85.8	154.7	125.2
Reduction in Investment Assets Managed by a Directors Investment Advisory Firm	(80.0)
Related Party Transaction, Expenses from Transactions with Related Party	0.3	0.4	0.3
Pension Plans, Defined Benefit [Member] \| Investment Management Services for Defined Benefit Plan [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	0.4	0.3	0.3
Assets under Management, Carrying Amount	$ 159.2	$ 148.6	$ 120.7

Amounts Invested in Defined Contribution Plan Mutual Fund Managed by a Director's Investment Advisory Firm

No definition available.

Name:	kmpr_AmountsInvestedInDefinedContributionPlanMutualFundManagedByDirectorsInvestmentAdvisoryFirm
Namespace Prefix:	kmpr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amounts Invested in Defined Contribution Plan Mutual Fund Managed by a Director's Investment Advisory Frim, Percentage of Total Defined Contribution Plan Investments

+ References

No definition available.

+ Details

Name:	kmpr_AmountsInvestedInDefinedContributionPlanMutualFundManagedByDirectorsInvestmentAdvisoryFirmPercentageOfTotalDefinedContributionPlanInvestments
Namespace Prefix:	kmpr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Investment Assets Managed by a Directors Investment Advisory Firm

+ References

No definition available.

+ Details

Name:	kmpr_InvestmentAssetsManagedByDirectorsInvestmentAdvisoryFirm
Namespace Prefix:	kmpr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Reduction in Investment Assets Managed by a Directors Investment Advisory Firm

+ References

No definition available.

+ Details

Name:	kmpr_ReductioninInvestmentAssetsManagedbyaDirectorsInvestmentAdvisoryFirm
Namespace Prefix:	kmpr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The carrying amount of assets an investment adviser manages on behalf of investors.

+ References

No definition available.

+ Details

Name:	us-gaap_AssetsUnderManagementCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 850

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

+ Details

Name:	us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_RelatedPartyTransactionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	dei_LegalEntityAxis=kmpr_TrinityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: