v2.4.0.6

Related Parties (Details) (Director [Member], USD $) In Millions, unless otherwise specified | 9 Months Ended
--- | ---
Sep. 30, 2012 | Sep. 30, 2011
Related Party Transaction [Line Items] |  |
Related Party Transaction Amount of Assets in Defined Contributions Plans | $ 21.6 |
Related Party Transaction Percent of Assets in Defined Contribution Plan Assets | 7.00% |
Trinity [Member] |  |
Related Party Transaction [Line Items] |  |
Related Party Transaction, Amounts of Transaction | 128.3 |
Related Party Transaction, Expenses from Transactions with Related Party | 0.2 | 0.2
Pension Plans, Defined Benefit [Member] |  |
Related Party Transaction [Line Items] |  |
Related Party Transaction, Expenses from Transactions with Related Party | 0.2 | 0.2
Related Party Transaction Amount of Assets Under Management in Defined Benefit Plans | $ 123.9 |

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- Definition Amounts Invested in Defined Contribution Plan Mutual Fund Managed by a Director's Investment Advisory Firm + References No definition available. + Details
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Namespace Prefix: | kmpr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- 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
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Namespace Prefix: | kmpr_
Data Type: | num:percentItemType
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Period Type: | instant

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- Definition Investment Assets Managed by a Directors Investment Advisory Firm + References No definition available. + Details
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Namespace Prefix: | kmpr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition Related Party Transaction Amount of Assets Under Management in Defined Benefit Plans + References No definition available. + Details
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Namespace Prefix: | kmpr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- 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 Statement of Financial Accounting Standard (FAS) -Number 57 -Paragraph 2 -Subparagraph c -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: 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
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration