Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2013

Fair Value Disclosures [Abstract]

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table Text Block]

The valuation of assets measured at fair value in the Company’s Condensed Consolidated Balance Sheet at December 31, 2012 is summarized below:

	Fair Value Measurements
(Dollars in Millions)	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total Fair Value
Fixed Maturities:
U.S. Government and Government Agencies and Authorities	$	135.8	$	293.1	$	—	$	428.9
States and Political Subdivisions	—		1,401.4		—		1,401.4
Corporate Securities:
Bonds and Notes	—		2,632.4		361.0		2,993.4
Redeemable Preferred Stocks	—		27.9		4.7		32.6
Mortgage and Asset-backed	—		3.8		0.1		3.9
Total Investments in Fixed Maturities	135.8		4,358.6		365.8		4,860.2
Equity Securities:
Preferred Stocks:
Finance, Insurance and Real Estate	—		79.2		—		79.2
Other Industries	—		15.3		6.0		21.3
Common Stocks:
Manufacturing	79.6		6.0		1.9		87.5
Other Industries	60.1		1.2		5.4		66.7
Other Equity Interests:
Exchange Traded Funds	125.9		—		—		125.9
Limited Liability Companies and Limited Partnerships	—		—		141.3		141.3
Total Investments in Equity Securities	265.6		101.7		154.6		521.9
Other Investments:
Trading Securities	4.5		—		—		4.5
Total	$	405.9	$	4,460.3	$	520.4	$	5,386.6

The valuation of assets measured at fair value in the Company’s Condensed Consolidated Balance Sheet at March 31, 2013 is summarized below:

	Fair Value Measurements
(Dollars in Millions)	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total Fair Value
Fixed Maturities:
U.S. Government and Government Agencies and Authorities	$	133.5	$	295.6	$	—	$	429.1
States and Political Subdivisions	—		1,401.8		—		1,401.8
Canadian Government and Provinces	—		0.6		—		0.6
Corporate Securities:
Bonds and Notes	—		2,635.6		343.5		2,979.1
Redeemable Preferred Stocks	—		8.6		4.4		13.0
Mortgage and Asset-backed	—		1.7		31.2		32.9
Total Investments in Fixed Maturities	133.5		4,343.9		379.1		4,856.5
Equity Securities:
Preferred Stocks:
Finance, Insurance and Real Estate	—		77.1		—		77.1
Other Industries	—		11.1		7.1		18.2
Common Stocks:
Manufacturing	87.4		6.8		1.7		95.9
Other Industries	56.7		1.4		5.8		63.9
Other Equity Interests:
Exchange Traded Funds	155.1		—		—		155.1
Limited Liability Companies and Limited Partnerships	—		—		143.9		143.9
Total Investments in Equity Securities	299.2		96.4		158.5		554.1
Other Investments:
Trading Securities	4.6		—		—		4.6
Total	$	437.3	$	4,440.3	$	537.6	$	5,415.2

Fair Value Inputs, Assets, Quantitative Information [Table Text Block]

The table below presents quantitative information about the significant unobservable inputs utilized by the Company in determining fair values for investments in corporate bonds and notes classified as Level 3.

(Dollars in Millions)	Unobservable Input	Total Fair Value		Range of Unobservable Inputs					Weighted Average Yield
Investment Grade Private Placements	Yield	$	108.3	1.2	%	-	5.9	%	3.8	%
Non-investment Grade:
Senior Debt	Yield	75.8		5.3		-	18.6		8.6
Junior Debt	Yield	148.4		8.3		-	24.3		14.1
Other Debt	Various	11.0
Bonds and Notes Classified as Level 3		$	343.5

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

Information by security type pertaining to the changes in the fair value of the Company’s investments classified as Level 3 for the three months endedMarch 31, 2013 is presented below:

	Fixed Maturities									Equity Securities
(Dollars in Millions)	Corporate Bonds and Notes			Redeemable Preferred Stocks			Mortgage and Asset- backed			Preferred and Common Stocks			Other Equity Interests			Total
Balance at Beginning of Period	$	361.0		$	4.7		$	0.1		$	13.3		$	141.3		$	520.4
Total Gains (Losses):
Included in Condensed Consolidated Statement of Income	(0.8		)	(0.3		)	—			—			(0.2		)	(1.3		)
Included in Other Comprehensive Income	(3.8		)	—			(0.3		)	1.5			(2.3		)	(4.9		)
Purchases	38.7			—			29.0			0.1			10.5			78.3
Settlements	(45.8		)	—			—			—			(5.4		)	(51.2		)
Sales	—			—			—			(0.3		)	—			(0.3		)
Transfers into Level 3	—			—			2.4			—			—			2.4
Transfers out of Level 3	(5.8		)	—			—			—			—			(5.8		)
Balance at End of Period	$	343.5		$	4.4		$	31.2		$	14.6		$	143.9		$	537.6

Information by security type pertaining to the changes in the fair value of the Company’s investments classified as Level 3 for the three months endedMarch 31, 2012 is presented below:

	Fixed Maturities							Equity Securities
(Dollars in Millions)	Corporate Bonds and Notes			Redeemable Preferred Stocks		Mortgage and Asset- backed		Preferred and Common Stocks			Other Equity Interests			Total
Balance at Beginning of Period	$	235.1		$	6.1	$	0.3	$	13.5		$	93.1		$	348.1
Total Gains (Losses):
Included in Condensed Consolidated Statement of Income	0.1			—		—		3.2			0.3			3.6
Included in Other Comprehensive Income	0.9			0.2		—		(1.2		)	1.1			1.0
Purchases	44.8			—		—		0.5			16.0			61.3
Settlements	(16.2		)	—		—		—			(4.0		)	(20.2		)
Sales	(0.3		)	—		—		(3.7		)	—			(4.0		)
Transfers into Level 3	0.9			—		—		—			—			0.9
Transfers out of Level 3	(6.1		)	—		—		—			—			(6.1		)
Balance at End of Period	$	259.2		$	6.3	$	0.3	$	12.3		$	106.5		$	384.6