Fair Value of Financial Instruments Level 3 Liabilities - Unobservable inputs (Details) (Level 3, USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Embedded derivatives EIA/VED
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Total Level 3 liabilities	153.9	91.9
Embedded derivatives EIA/VED | Income Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Mortality rate		97.00%
CSA Rate	3.08%	3.23%
Embedded derivatives EIA/VED | Minimum | Income Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Swap curve	0.24%	0.19%
Mortality rate	97.00%
Lapse rate	0.04%	0.02%
Embedded derivatives EIA/VED | Maximum | Income Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Swap curve	2.55%	3.79%
Mortality rate	105.00%	103.00%
Lapse rate	46.44%	47.15%
Embedded derivatives GMAB/GMWB
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Total Level 3 liabilities	(6.4)	(4.1)
Embedded derivatives GMAB/GMWB | Income Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Mortality rate	105.00%	105.00%
CSA Rate	3.08%	3.23%
Embedded derivatives GMAB/GMWB | Minimum | Income Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Swap curve	0.21%	0.15%
Volatility surface	9.89%	10.85%
Lapse rate	0.00%	0.00%
Embedded derivatives GMAB/GMWB | Maximum | Income Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Swap curve	2.76%	4.15%
Volatility surface	67.34%	46.33%
Lapse rate	40.00%	40.00%