Fair Value (Tables)

9 Months Ended

Sep. 30, 2011

Fair Value [Abstract]

Fair Value Of Financial Instruments

(in millions)	September 30, 2011				December 31, 2010
	Carrying Value		Fair Value		Carrying Value		Fair Value
Financial Assets
Cash and cash equivalents	$	922.7	$	922.7	$	290.4	$	290.4
Fixed maturities		6,227.6		6,227.6		4,797.9		4,797.9
Equity securities		246.3		246.3		128.6		128.6
Mortgage loans		4.9		5.2		5.5		5.8
Other investments		143.9		143.9		—		—
Derivative instruments		5.4		5.4		—		—
Total financial assets	$	7,550.8	$	7,551.1	$	5,222.4	$	5,222.7
Financial Liabilities
Legal indemnities		5.6		5.6		5.4		5.4
Debt		901.6		986.2		605.9		603.9
Total financial liabilities	$	907.2	$	991.8	$	611.3	$	609.3

Fair Value Of Assets On A Recurring Basis

	September 30, 2011
(in millions)	Total		Level 1		Level 2		Level 3
Fixed maturities:
U.S. Treasury and government agencies	$	279.0	$	153.0	$	126.0	$	—
Foreign government		302.9				302.9
Municipal		1,032.9		—		1,017.1		15.8
Corporate		3,291.4		—		3,268.9		22.5
Residential mortgage-backed, U.S. agency backed		701.0		—		701.0		—
Residential mortgage-backed, non-agency		163.7		—		158.2		5.5
Commercial mortgage-backed		346.1		—		333.9		12.2
Asset-backed		110.6		—		88.8		21.8
Total fixed maturities		6,227.6		153.0		5,996.8		77.8
Equity securities		237.4		122.9		89.0		25.5
Other investments		143.9		—		143.9		—
Total investment assets at fair value	$	6,608.9	$	275.9	$	6,229.7	$	103.3
Derivative instruments	$	5.4	$	—	$	5.4	$	—

	December 31, 2010
	Total		Level 1		Level 2		Level 3
Fixed maturities:
U.S. Treasury and government agencies	$	261.2	$	124.0	$	137.2	$	—
Municipal		954.7		—		938.1		16.6
Corporate		2,420.4		—		2,392.2		28.2
Residential mortgage-backed, U.S. agency backed		600.4		—		600.4		—
Residential mortgage-backed, non-agency		133.7		—		132.9		0.8
Commercial mortgage-backed		366.6		—		361.1		5.5
Asset-backed		60.9		—		47.4		13.5
Total fixed maturities		4,797.9		124.0		4,609.3		64.6
Equity securities		120.0		106.6		10.5		2.9
Total investment assets at fair value	$	4,917.9	$	230.6	$	4,619.8	$	67.5

Fair Value On Recurring Basis Using Significant Unobservable Inputs (Level 3)

	Fixed Maturities
(in millions)	Municipal			Corporate			Residential mortgage- backed, non-agency			Commercial mortgage- backed			Asset- backed			Total			Equities			Total Assets
Three Months Ended September 30, 2011
Balance July 1, 2011	$	16.1		$	36.8		$	0.5		$	5.1		$	13.5		$	72.0		$	2.9		$	74.9
Transfers into Level 3		—			6.9			—			—			—			6.9			—			6.9
Transfers out of Level 3		—			(8.8	)		(0.5	)		—			—			(9.3	)		—			(9.3	)
Total gains (losses):
Included in earnings		—			0.1			—			—			—			0.1			—			0.1
Included in other comprehensive income		—			(0.3	)		—			—			(0.2	)		(0.5	)		(1.6	)		(2.1	)
Purchases and sales:
Purchases		—			—			—			7.3			—			7.3			—			7.3
Chaucer acquisition		—			0.1			5.6			—			8.8			14.5			24.2			38.7
Sales		(0.3	)		(12.3	)		(0.1	)		(0.2	)		(0.3	)		(13.2	)		—			(13.2	)
Balance September 30, 2011	$	15.8		$	22.5		$	5.5		$	12.2		$	21.8		$	77.8		$	25.5		$	103.3
Three Months Ended September 30, 2010
Balance July 1, 2010	$	14.9		$	31.2		$	1.1		$	5.9		$	15.7		$	68.8		$	2.8		$	71.6
Transfers into Level 3		—			3.3			—			—			—			3.3			—			3.3
Transfers out of Level 3		—			(2.7	)		—			—			—			(2.7	)		—			(2.7	)
Total gains:
Included in earnings		—			—			—			—			0.1			0.1			—			0.1
Included in other comprehensive income		0.1			0.3			—			—			0.4			0.8			—			0.8
Purchases and sales:
Purchases		—			0.4			—			—			—			0.4			1.0			1.4
Sales		(0.4	)		(0.3	)		(0.1	)		(0.2	)		(1.8	)		(2.8	)		—			(2.8	)
Balance September 30, 2010	$	14.6		$	32.2		$	1.0		$	5.7		$	14.4		$	67.9		$	3.8		$	71.7
Nine Months Ended September 30, 2011
Balance January 1, 2011	$	16.6		$	28.2		$	0.8		$	5.5		$	13.5		$	64.6		$	2.9		$	67.5
Transfers into Level 3		—			10.6			—			—			—			10.6			—			10.6
Transfers out of Level 3		—			(15.3	)		(0.5	)		—			—			(15.8	)		—			(15.8	)
Total gains (losses):
Included in earnings		—			0.1			—			—			—			0.1			(0.5	)		(0.4	)
Included in other comprehensive income		0.1			—			—			—			0.1			0.2			(1.1	)		(0.9	)
Purchases and sales:
Purchases		—			11.8			—			7.3			—			19.1			—			19.1
Chaucer acquisition		—			0.1			5.6			—			8.8			14.5			24.2			38.7
Sales		(0.9	)		(13.0	)		(0.4	)		(0.6	)		(0.6	)		(15.5	)		—			(15.5	)
Balance September 30, 2011	$	15.8		$	22.5		$	5.5		$	12.2		$	21.8		$	77.8		$	25.5		$	103.3
Nine Months Ended September 30, 2010
Balance January 1, 2010	$	15.5		$	28.9		$	—		$	6.2		$	9.2		$	59.8		$	2.8		$	62.6
Transfers into Level 3		—			9.9			—			—			6.9			16.8			—			16.8
Transfer out of Level 3		—			(2.7	)		—			—			(2.0	)		(4.7	)		—			(4.7	)
Total gains (losses):
Included in earnings		—			0.1			—			—			0.1			0.2			(0.3	)		(0.1	)
Included in other comprehensive income		0.3			1.3			—			—			0.6			2.2			0.3			2.5
Purchases and sales:
Purchases		—			0.7			1.4			—			2.0			4.1			1.0			5.1
Sales		(1.2	)		(6.0	)		(0.4	)		(0.5	)		(2.4	)		(10.5	)		—			(10.5	)
Balance September 30, 2010	$	14.6		$	32.2		$	1.0		$	5.7		$	14.4		$	67.9		$	3.8		$	71.7

Schedule Of Gain (Loss) Due To Change In Fair Value Level 3 Assets

	Three Months Ended September 30,
	2011						2010
(in millions)	Other-than- temporary impairments		Net realized investment gains		Total		Other-than- temporary impairments		Net realized investment gains		Total
Level 3 Assets:
Fixed maturities:
Corporate	$	—	$	0.1	$	0.1	$	—	$	—	$	—
Asset Backed		—		—		—		—		0.1		0.1
Total assets	$	—	$	0.1	$	0.1	$	—	$	0.1	$	0.1

	Nine Months Ended September 30,
	2011								2010
(in millions)	Other-than- temporary impairments			Net realized investment gains		Total			Other-than- temporary impairments			Net realized investment gains		Total
Level 3 Assets:
Fixed maturities:
Corporate	$	—		$	0.1	$	0.1		$	—		$	0.1	$	0.1
Asset Backed		—			—		—			—			0.1		0.1
Equity securities		(0.5	)		—		(0.5	)		(0.3	)		—		(0.3	)
Total assets	$	(0.5	)	$	0.1	$	(0.4	)	$	(0.3	)	$	0.2	$	(0.1	)