Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Document Period End Date	Dec. 31, 2019
Property, Plant and Equipment, Useful Life	40 years
Other Asset Impairment Charges	$ 4.0	$ 5.0	$ 25.0
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	99.0	97.0
Property, Plant and Equipment, Gross	244.0	249.0
Depreciation	18.0	18.0	17.0
Goodwill	7.0	7.0
Present Value of Future Insurance Profits, Net	5.0
Amortization of Value of Business Acquired (VOBA)	0.7	0.4	0.3
Values Of Business Acquired Distribution Agreements And Customer Relationships	33.0	41.0
Accumulated Amortization Of Values Of Business Acquired Distribution Agreements And Customer Relationships	88.0	80.0
Amortization Of Values Of Business Acquired Distribution Agreements And Customer Relationships	8.0	8.0	9.0
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	8.0
Finite-Lived Intangible Assets, Amortization Expense, Year Two	7.0
Finite-Lived Intangible Assets, Amortization Expense, Year Three	6.0
Finite-Lived Intangible Assets, Amortization Expense, Year Four	6.0
Finite-Lived Intangible Assets, Amortization Expense, Year Five	6.0
Capitalized Computer Software, Net	151.0	150.0
Capitalized Computer Software, Amortization	$ 31.0	27.0	$ 36.0
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
Other Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	10 years
Accumulated Amortization Of Values Of Business Acquired Distribution Agreements And Customer Relationships	$ 8.0	$ 4.0
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	4.0
Finite-Lived Intangible Assets, Amortization Expense, Year Two	4.0
Finite-Lived Intangible Assets, Amortization Expense, Year Three	4.0
Finite-Lived Intangible Assets, Amortization Expense, Year Four	4.0
Finite-Lived Intangible Assets, Amortization Expense, Year Five	$ 4.0
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Collateral Obtained Percent Of Fair Value Reverse Repurchase Agreements	100.00%
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Collateral Obtained Percent Of Fair Value Reverse Repurchase Agreements	105.00%