Acquisition of Business (Narrative) (Details) $ / shares in Units, $ in Millions			3 Months Ended	12 Months Ended
	Jul. 13, 2018 USD ($)	Jul. 02, 2018 USD ($) $ / shares shares	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) agent
Business Acquisition [Line Items]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares		44,010
Infinity [Member]
Business Acquisition [Line Items]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares		13,184,107
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable		$ 982.5
Payments to Acquire Businesses, Gross		564.6
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable, Fair Value of the Restricted Units Granted		3.3
Business Combination, Consideration Transferred, Other		1.6
Business Combination, Contingent Consideration, Liability, Noncurrent		1.7
Business Combination, Consideration Transferred, Liabilities Incurred	$ 110.0
Business Combination, Number of Agents | agent				10,600
Premiums Written, Net				$ 1,400.0
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Legal Accruals, Other LIabilities and Tax Related Balance			$ 22.9
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Property, Plant, and Equipment			1.7
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Goodwill			$ 21.2
Kemper's 2-12-18 Closing Price per share [Member] | Infinity [Member]
Business Acquisition [Line Items]
Total Merger Value		$ 1,500.0
Share Price | $ / shares		$ 74.53
Secured Debt [Member] | Infinity [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred, Liabilities Incurred		$ 250.0