Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Collateral Obtained Percent Of Fair Value Reverse Repurchase Agreements	100.00%
Property, Plant and Equipment, Useful Life	40 years
Other Asset Impairment Charges	$ 24.5	$ 0.6	$ 6.0
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	79.4	60.8
Property, Plant and Equipment, Gross	236.1	221.7
Depreciation	17.2	16.6	17.1
Capital Leased Assets, Gross	136.3	145.7
Capital Leases, Lessee Balance Sheet, Assets by Major Class, Accumulated Depreciation	30.5	21.0
Amortization of Leased Asset	9.4	9.6	10.0
Goodwill	7.0	7.0
Present Value of Future Insurance Profits, Net	3.3	3.1
Accumulated Amortization Of Value Of Business Acquired VOBA	14.6	14.3
Amortization of Value of Business Acquired (VOBA)	0.3	0.5	0.4
Values Of Business Acquired Distribution Agreements And Customer Relationships	52.3	61.2
Accumulated Amortization Of Values Of Business Acquired Distribution Agreements And Customer Relationships	72.1	63.2
Amortization Of Values Of Business Acquired Distribution Agreements And Customer Relationships	8.9	9.3	9.5
Future Amortization Expense, Year One	8.6
Future Amortization Expense, Year Two	8.3
Future Amortization Expense, Year Three	7.8
Future Amortization Expense, Year Four	6.9
Future Amortization Expense, Year Five	6.6
Capitalized Computer Software, Net	145.5	139.8
Capitalized Computer Software, Amortization	$ 35.7	$ 10.3	$ 14.0
Value of Customer Relationships Acquired [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	15 years
Value of Distribution Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	15 years