XML 79 R67.htm IDEA: XBRL DOCUMENT
v3.25.3

Derivatives - Narrative (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024
Treasury Lock, 2016 |  |  |  |
Derivative [Line Items] |  |  |  |
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  | $ (4.5) |
Derivative Instruments, Amortization |  |  | 0.1 |
Treasury Lock, 2022 |  |  |  |
Derivative [Line Items] |  |  |  |
Gain (Loss) on Derivative Instruments, Net, Pretax |  |  | 5.9 |
Derivative Instruments, Amortization | $ 0.1 | $ 0.4 | 0.1 | $ 0.4
Derivatives, Gain (Loss), Reclassified to Earnings, Net of Tax | $ 3.8 |  | $ 3.8 |

X
- Definition Derivative Instruments, Amortization + References No definition available. + Details
Name: | kmpr_DerivativeInstrumentsAmortization
Namespace Prefix: | kmpr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Derivatives, Gain (Loss), Reclassified to Earnings, Net of Tax + References No definition available. + Details
Name: | kmpr_DerivativesGainLossReclassifiedToEarningsNetOfTax
Namespace Prefix: | kmpr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- 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 Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 20 -Name Accounting Standards Codification -Section 25 -Paragraph 6A -Publisher FASB -URI https://asc.fasb.org/1943274/2147480682/815-20-25-6A Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480237/815-40-50-5 + Details
Name: | us-gaap_DerivativeLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4A -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4A + Details
Name: | us-gaap_GainLossOnDerivativeInstrumentsNetPretax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=kmpr_TreasuryLock2016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=kmpr_TreasuryLock2022Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |