Income Taxes - Schedule of Current and Deferred Income Tax Liabilities (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Deferred Income Tax Liabilities	$ 0	$ 15.1
Unrecognized Tax Benefits	6.6	6.4
Liabilities for Income Taxes	$ 6.6	$ 21.5

The Sum total of (a) the carrying amount as of the balance sheet date of the unpaid sum of the known and estimated amounts payable to satisfy all currently due domestic and foreign income tax obligations,(b) the cumulative amount for all deferred tax liabilities as of the balance sheet date arising from temporary differences between accounting income in accordance with generally accepted accounting principles and tax-basis income that will result in future taxable income exceeding future accounting income and (c) the gross amount of unrecognized tax benefits (tax reductions recognized in financial reports but excluded from tax returns) pertaining to uncertain tax positions taken in tax returns as of the beginning balance sheet date, excluding amounts pertaining to examined tax returns.

No definition available.

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Namespace Prefix:	kmpr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant