Investments (Tables)

3 Months Ended

Mar. 31, 2012

Investments [Abstract]

Amortized Cost And Fair Value Of Available-For-Sale Fixed Maturities, Cost And Fair Value Of Equity Securities

		$6,141.2		$6,141.2		$6,141.2		$6,141.2		$6,141.2
	March 31, 2012
(in millions)	Amortized Cost or Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value		OTTI Unrealized Losses
Fixed maturities:
U.S. Treasury and government agencies	$	224.4	$	6.9	$	0.3	$	231.0	$	—
Foreign government		273.3		0.6		0.1		273.8		—
Municipal		933.3		74.6		2.9		1,005.0		—
Corporate		3,345.9		218.4		18.7		3,545.6		10.6
Residential mortgage-backed		778.1		40.7		7.4		811.4		5.7
Commercial mortgage-backed		373.1		14.6		0.3		387.4		—
Asset-backed		213.1		4.3		1.0		216.4		—
Total fixed maturities	$	6,141.2	$	360.1	$	30.7	$	6,470.6	$	16.3
Equity securities	$	315.5	$	25.5	$	6.9	$	334.1	$	—
	December 31, 2011
	Amortized Cost or Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value		OTTI Unrealized Losses
Fixed maturities:
U.S. Treasury and government agencies	$	261.7	$	7.8	$	0.2	$	269.3	$	—
Foreign government		239.1		0.4		0.5		239.0		—
Municipal		964.5		67.4		3.9		1,028.0		—
Corporate		3,218.2		197.7		40.3		3,375.6		13.8
Residential mortgage-backed		816.1		40.9		8.4		848.6		6.1
Commercial mortgage-backed		367.6		12.5		1.0		379.1		—
Asset-backed		141.5		4.3		0.7		145.1		—
Total fixed maturities	$	6,008.7	$	331.0	$	55.0	$	6,284.7	$	19.9
Equity securities	$	239.9	$	15.3	$	8.8	$	246.4	$	—

Maturities Of Available-For-Sale Debt Securities

(in millions)	March 31, 2012
	Amortized Cost		Fair Value
Due in one year or less	$	441.4	$	446.2
Due after one year through five years		2,092.0		2,188.4
Due after five years through ten years		1,592.2		1,720.2
Due after ten years		651.3		700.6
		4,776.9		5,055.4
Mortgage-backed and asset-backed securities		1,364.3		1,415.2
Total fixed maturities	$	6,141.2	$	6,470.6

Fixed Maturities And Equity Securities In An Unrealized Loss Position

		$ 1,513.2		$ 1,513.2		$ 1,513.2		$ 1,513.2		$ 1,513.2		$ 1,513.2
	March 31, 2012
	12 months or less				Greater than 12 months				Total
(in millions)	Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value
Fixed maturities:
Investment grade:
U.S. Treasury and government agencies	$	0.3	$	42.2	$	—	$	—	$	0.3	$	42.2
Foreign governments		0.1		74.2		—		—		0.1		74.2
Municipal		0.5		21.9		2.4		42.2		2.9		64.1
Corporate		4.6		364.8		4.7		32.6		9.3		397.4
Residential mortgage-backed		4.6		52.4		2.0		13.9		6.6		66.3
Commercial mortgage-backed		0.1		24.3		0.2		4.8		0.3		29.1
Asset-backed		0.4		56.3		—		—		0.4		56.3
Total investment grade		10.6		636.1		9.3		93.5		19.9		729.6
Below investment grade:
Corporate		7.4		93.3		2.0		12.4		9.4		105.7
Residential mortgage-backed		0.8		16.4		—		—		0.8		16.4
Asset-backed		0.6		1.0		—		—		0.6		1.0
Total below investment grade		8.8		110.7		2.0		12.4		10.8		123.1
Total fixed maturities		19.4		746.8		11.3		105.9		30.7		852.7
Equity securities		6.5		88.6		0.4		10.6		6.9		99.2
Total	$	25.9	$	835.4	$	11.7	$	116.5	$	37.6	$	951.9

		$ 1,513.2		$ 1,513.2		$ 1,513.2		$ 1,513.2		$ 1,513.2		$ 1,513.2
	December 31, 2011
	12 months or less				Greater than 12 months				Total
(in millions)	Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value
Fixed maturities:
Investment grade:
U.S. Treasury and government agencies	$	0.2	$	57.7	$	—	$	—	$	0.2	$	57.7
Foreign governments		0.5		148.8		—		—		0.5		148.8
Municipal		0.5		28.0		3.4		58.8		3.9		86.8
Corporate		19.9		699.6		8.2		35.6		28.1		735.2
Residential mortgage-backed		5.1		115.8		2.4		9.9		7.5		125.7
Commercial mortgage-backed		0.7		58.0		0.3		4.6		1.0		62.6
Asset-backed		0.2		67.6		—		—		0.2		67.6
Total investment grade		27.1		1,175.5		14.3		108.9		41.4		1,284.4
Below investment grade:
Corporate		8.5		118.0		3.7		14.7		12.2		132.7
Residential mortgage-backed		0.9		8.0		—		—		0.9		8.0
Asset-backed		0.5		0.9		—		—		0.5		0.9
Total below investment grade		9.9		126.9		3.7		14.7		13.6		141.6
Total fixed maturities		37.0		1,302.4		18.0		123.6		55.0		1,426.0
Equity securities		8.8		87.2		—		—		8.8		87.2
Total	$	45.8	$	1,389.6	$	18.0	$	123.6	$	63.8	$	1,513.2

Proceeds From Sale Of Available-For-Sale Securities

	Three Months Ended March 31,
	2012						2011
(in millions)	Proceeds from Sales		Gross Gains		Gross Losses		Proceeds from Sales		Gross Gains		Gross Losses
Fixed maturities	$	279.2	$	4.7	$	1.1	$	106.5	$	4.2	$	0.8
Equity securities		0.7		—		0.2		—		—		—

Rollforward Of Cumulative Amounts Related To Credit Loss Portion Of OTTI Losses

(in millions)	Three Months Ended March 31,
	2012			2011
Credit losses as of the beginning of the period	$	14.5		$	16.7
Credit losses for which an OTTI was not previously recognized		0.1			—
Additional credit losses on securities for which an OTTI was previously recognized		0.3			0.2
Reductions for securities sold, matured or called during the period		(1.4	)		(0.6	)
Credit losses as of the end of the period	$	13.5		$	16.3