Investments Investments - Schedule of Other Investments (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Investments Disclosures [Abstract]
Loans to Policyholders at Unpaid Principal	$ 284.5us-gaap_LoansInsurancePolicy	$ 283.4us-gaap_LoansInsurancePolicy
Real Estate at Depreciated Cost	160.3us-gaap_RealEstateInvestmentPropertyNet	160.9us-gaap_RealEstateInvestmentPropertyNet
Trading Securities, Fair Value Disclosure	4.9us-gaap_TradingSecurities	4.9us-gaap_TradingSecurities
Other	0.4kmpr_OtherInvestmentsOther	0.4kmpr_OtherInvestmentsOther
Total	$ 450.1us-gaap_OtherInvestments	$ 449.6us-gaap_OtherInvestments

Amount before allowance of loans made to policy and contract holders using their life insurance contracts' cash value or separate accounts as collateral. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums over and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(a)(7))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.1(e))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Subparagraph e

-Article 7

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