Fair Value of Financial Instruments Fair Value of Financial Instruments - Quantitative Estimates for Level 3 Liabilities (Details) (Level 3, USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
EIA/VED Embedded Derivative
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Embedded derivatives	$ 97.2	$ 78.9
EIA/VED Embedded Derivative | Income Approach Valuation Technique
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, CSA Rate	2.92%		3.23%
EIA/VED Embedded Derivative | Minimum | Income Approach Valuation Technique
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Swap curve	0.17%		0.19%
Mortality rate	97.00%		97.00%
Lapse rate	0.02%		0.02%
EIA/VED Embedded Derivative | Maximum | Income Approach Valuation Technique
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Swap curve	3.40%		3.79%
Mortality rate	103.00%	103.00%
Lapse rate	35.00%		47.15%
GMAB/GMWB Embedded Derivatives
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Embedded derivatives	$ (3.5)	$ (4.1)
GMAB/GMWB Embedded Derivatives | Income Approach Valuation Technique
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Mortality rate	105.00%		105.00%
Fair Value Inputs, CSA Rate	2.92%		3.23%
GMAB/GMWB Embedded Derivatives | Minimum | Income Approach Valuation Technique
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Swap curve	0.14%		0.15%
Lapse rate	0.00%		0.00%
Volatility surface	9.57%		10.85%
GMAB/GMWB Embedded Derivatives | Maximum | Income Approach Valuation Technique
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Swap curve	3.70%		4.15%
Lapse rate	40.00%		40.00%
Volatility surface	46.36%		46.33%