Related Parties (Details) (Director [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2014	Mar. 31, 2013
Related Party Transaction [Line Items]
Amounts Invested in Defined Contribution Plan Mutual Fund Managed by a Directors Investment Advisory Firm	$ 22.4
Amounts Invested in Defined Contribution Plan Mutual Fund Managed by a Directors Investment Advisory Firm Percentage of Total Defined Contribution Plan Investments	6.30%
Trinity [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Amounts of Transaction	155.7
Related Party Transaction, Expenses from Transactions with Related Party	0.1	0.1
Pension Plan, Defined Benefit [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	0.1	0.1
Pension Plan, Defined Benefit [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Amounts of Transaction	$ 149.2

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

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