Income Taxes - Schedule of Temporary Differences That Give Rise to Net Deferred Income Tax Assets (Liabilities) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Deferred Income Tax Assets:
Insurance Reserves	$ 78.7	$ 76.4
Unearned Premium Reserves	35.5	40.2
Tax Capitalization of Policy Acquisition Costs	73.0	73.3
Payroll and Employee Benefit Accruals	74.0	38.8
Net Operating Loss Carryforward	31.7	53.3
Other	9.8	12.6
Total Deferred Income Tax Assets	302.7	294.6
Deferred Income Tax Liabilities:
Investments	160.1	80.0
Deferred Policy Acquisition Costs	106.1	106.0
Value of Insurance in Force Acquired	17.7	20.2
Goodwill and Licenses	28.4	26.8
Depreciable Assets	7.4	26.0
Other	4.5	3.8
Total Deferred Income Tax Liabilities	324.2	262.8
Net Deferred Income Tax Liabilities	$ (21.5)	$ 31.8