Related Parties (Details) - FS&C [Member] - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Trinity [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Amounts of Assets Managed by Investment Advisory Firm under Director's Management			$ 85.8
Related Party Transaction, Expenses from Transactions with Related Party		$ 0.1	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	$ 0.8	0.4	0.4
Assets under Management, Carrying Amount	$ 148.4	$ 137.2	$ 159.2

Investment Assets Managed by a Directors Investment Advisory Firm

No definition available.

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

- 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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ 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_RelatedPartyTransactionsByRelatedPartyAxis=kmpr_FSCMember
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:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=kmpr_InvestmentManagementServicesforDefinedBenefitPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: