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Investment Securities (Investment Gains (Losses) For Level 3) (Details) (Level 3 Inputs, USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Investment securities
Total pre-tax gains (losses) included in earnings attributable to unrealized investment gains (losses) for Level 3 investments	$ 17.7	$ (45.6)	$ 30.0
Fixed maturity investments
Investment securities
Total pre-tax gains (losses) included in earnings attributable to unrealized investment gains (losses) for Level 3 investments	7.7	(12.2)	10.2
Common equity securities
Investment securities
Total pre-tax gains (losses) included in earnings attributable to unrealized investment gains (losses) for Level 3 investments	3.0	(16.6)	(19.2)
Convertible fixed maturity investments
Investment securities
Total pre-tax gains (losses) included in earnings attributable to unrealized investment gains (losses) for Level 3 investments	0	0	0
Other long-term investments
Investment securities
Total pre-tax gains (losses) included in earnings attributable to unrealized investment gains (losses) for Level 3 investments	$ 7.0	$ (16.8)	$ 39.0

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- Details

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- Definition

The aggregate increase (decrease) in the market value of unsold investments whose gains (losses) are included in earnings.

+ References

No definition available.

+ Details

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