Investments - Schedule of Other Than Temporary Impairment (Details) (Fixed Maturities [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Fixed Maturities [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Balance at Beginning of Period	$ 4.6	$ 3.9
Additions for Previously Unrecognized OTTI Credit Losses	0.7	0
Reductions to Previously Recognized OTTI Credit Losses	0	(0.1)
From Status of Credit Loss to Status of Intent-to-sell or Required-to-sell	1.1	0
Reductions for Investments Sold During Period	(0.1)	0
Balance at End of Period	$ 4.1	$ 3.8

The cumulative amount of credit losses recognized in earnings related to debt securities held for which a portion of an other than temporary impairment (OTTI) was recognized in other comprehensive income (a component of shareholders' equity).

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This item represents reductions in the amount of cumulative losses recognized in earnings for other than temporary impairments (OTTI) for which a portion of the impairment had been recognized in other comprehensive income (a component of shareholders' equity) due to a change in status of the impaired security because of a change in the entity's intent to either sell the impaired security or it has become more likely than not that the entity will be required to sell the security before recovery of its cost basis.

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