Fair Values of Financial Instruments Level 3 Quantitative Sensitivity Analysis (Details) (Fair Value, Inputs, Level 3 [Member], USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012
Mortgage/Asset-backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Fair Value, Investments, Valuation Techniques	- Discount for Size
Investments, Fair Value Disclosure, Significant Assumptions	5.65% - 5.75%/5.73%	[1]
All Other Corporate Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Fair Value, Investments, Valuation Techniques	- Change in Benchmark Reference - Discount for Size - Lack of Marketability - Volatility of Credit - Market Convention
Investments, Fair Value Disclosure, Significant Assumptions	0.90% - 1.60%/1.02% 0.50% - 0.50%/0.50% 0.01% - 1.00%/0.41% (0.50)% - 7.72%/1.32% Priced at Par	[1],[2],[3],[4],[5]
Corporate Bond Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Fair Value, Investments, Valuation Techniques	- Comparability Adjustment
Investments, Fair Value Disclosure, Significant Assumptions	0.50% - 0.50%/0.50%	[6]
Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Fair Value, Investments, Valuation Techniques	- Market Convention
Investments, Fair Value Disclosure, Significant Assumptions	Priced at Cost or Owner's Equity	[3]
Embedded Derivative in Modified Coinsurance Arrangement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Fair Value, Derivative Financial Instruments, Liabilities, Valuation Techniques	- Projected Liability Cash Flows
Investments, Fair Value Disclosure, Significant Assumptions	Actuarial Assumptions	[7]
Estimate of Fair Value, Fair Value Disclosure [Member] | Mortgage/Asset-backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Fixed Maturity Securities	0.6
Estimate of Fair Value, Fair Value Disclosure [Member] | All Other Corporate Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Fixed Maturity Securities	330.0
Estimate of Fair Value, Fair Value Disclosure [Member] | Corporate Bond Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Fixed Maturity Securities	39.6
Estimate of Fair Value, Fair Value Disclosure [Member] | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Equity Securities	4.0
Estimate of Fair Value, Fair Value Disclosure [Member] | Embedded Derivative in Modified Coinsurance Arrangement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Liability	(126.7)

[1] Represents basis point adjustments based on issue/issuer size relative to the benchmark

[2] Represents basis point adjustments for credit-specific factors

[3] Represents a decision to price based on par value, cost, or owner's equity when limited data is available

[4] Represents basis point adjustments to apply a discount due to the illiquidity of an investment

[5] Represents basis point adjustments for changes in benchmark spreads associated with various ratings categories

[6] Represents basis point adjustments for changes in benchmark spreads associated with various industry sectors

[7] Represents various actuarial assumptions required to derive the liability cash flows including incidence, termination, and lapse rates