Investments - Schedule of Investments (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2011	Dec. 31, 2010
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Debt Securities	$ 4,573.2	$ 4,475.3
Available-for-sale Securities, Equity Securities	503.0	550.4
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Available-for-sale Securities, Debt Maturities, after One Through Five Years, Fair Value	466.6
Available-for-sale Securities, Debt Maturities, within One Year, Fair Value	93.9
Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Fair Value	957.5
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value	2,742.2
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value	313.0
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	460.5	617.9
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(8.2)	(21.5)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	97.9	122.2
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	(7.5)	(12.7)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	558.4	740.1
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	(15.7)	(34.2)
Available For Sale Securities Continuous Unrealized Loss Position Aggregate Losses Related to Securities that have Previously Recognized Foregin Currency Impairment	0.1	(0.1)
Number of Issuers of Available for Sales Securities Continuous Unrealized Loss Possition Aggregate Losses Related to Securities that have Previously Recognized Foreign Currency impairment	1	1
Percentage of Unrealized Loss Postion to Amortized Cost Basis of Available for Sale Security Average		4.00%
Accrued Expenses and Other Liabilities	548.0	437.8
External Credit Rating, Investment Grade [Member] | Debt Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	10.2	(28.1)
External Credit Rating, Non Investment Grade [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available For Sale Securities Continuous Unrealized Loss Position Aggregate Losses Related to Securities that have Previously Recognized Foregin Currency Impairment	0.1	(0.1)
Percentage of Unrealized Loss Postion to Amortized Cost Basis of Available for Sale Security Average	3.00%
External Credit Rating, Non Investment Grade [Member] | Debt Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	3.5	(4.1)
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	70.2	103.2
Available-for-sale Securities, Gross Unrealized Losses	(2.0)	(2.0)
Available-for-sale Securities, Equity Securities	503.0	550.4
Available-for-sale Equity Securities, Amortized Cost Basis	434.8	449.2
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	75.2	20.1
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(1.5)	(0.8)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	6.9	13.2
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	(0.5)	(1.2)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	82.1	33.3
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	(2.0)	(2.0)
Preferred Stock Finance Insurance and Real Estate [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	4.4	3.5
Available-for-sale Securities, Gross Unrealized Losses	(0.1)	(0.2)
Available-for-sale Securities, Equity Securities	98.6	97.7
Available-for-sale Equity Securities, Amortized Cost Basis	94.3	94.4
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0	3.0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	2.3	2.6
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	(0.1)	(0.2)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	2.3	5.6
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	(0.1)	(0.2)
Preferred Stocks Other Industries [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	2.4	7.6
Available-for-sale Securities, Gross Unrealized Losses	(0.1)	(0.2)
Available-for-sale Securities, Equity Securities	20.5	27.4
Available-for-sale Equity Securities, Amortized Cost Basis	18.2	20.0
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	1.7	0.7
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0	(0.1)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	2.8	2.8
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	(0.1)	(0.1)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	4.5	3.5
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	(0.1)	(0.2)
Common Stock Intermec [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	26.8	50.6
Available-for-sale Securities, Gross Unrealized Losses	0	0
Available-for-sale Securities, Equity Securities	97.1	137.5
Available-for-sale Equity Securities, Amortized Cost Basis	70.3	86.9
Common Stocks Manufacturing [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	15.0	14.6
Available-for-sale Securities, Gross Unrealized Losses	0	(0.3)
Available-for-sale Securities, Equity Securities	78.6	89.6
Available-for-sale Equity Securities, Amortized Cost Basis	63.6	75.3
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	1.3	7.9
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0	(0.3)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	1.7
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1.3	9.6
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	0	(0.3)
Common Stocks Other Industries [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	7.1	6.6
Available-for-sale Securities, Gross Unrealized Losses	(0.7)	(0.1)
Available-for-sale Securities, Equity Securities	45.2	43.8
Available-for-sale Equity Securities, Amortized Cost Basis	38.8	37.3
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	8.2	6.3
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(0.7)	(0.1)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	8.2	6.3
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	(0.7)	(0.1)
Exchange Traded Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	0	2.7
Available-for-sale Securities, Gross Unrealized Losses	(0.2)	0
Available-for-sale Securities, Equity Securities	82.9	79.2
Available-for-sale Equity Securities, Amortized Cost Basis	83.1	76.5
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	44.2
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(0.2)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	44.2
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	(0.2)
Partnership Interest [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	14.5	17.6
Available-for-sale Securities, Gross Unrealized Losses	(0.9)	(1.2)
Available-for-sale Securities, Equity Securities	80.1	75.2
Available-for-sale Equity Securities, Amortized Cost Basis	66.5	58.8
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	19.8	2.2
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(0.6)	(0.3)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	1.8	6.1
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	(0.3)	(0.9)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	21.6	8.3
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	(0.9)	(1.2)
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	305.1	266.7
Available-for-sale Securities, Gross Unrealized Losses	(13.7)	(32.2)
Available-for-sale Securities, Debt Securities	4,573.2	4,475.3
Available-for-sale Debt Securities, Amortized Cost Basis	4,281.8	4,240.8
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	385.3	597.8
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(6.7)	(20.7)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	91.0	109.0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	(7.0)	(11.5)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	476.3	706.8
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	(13.7)	(32.2)
Accrued Expenses and Other Liabilities	90.2	0
US Government and Government Agencies and Authorities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	32.5	28.4
Available-for-sale Securities, Gross Unrealized Losses	(0.2)	(0.1)
Available-for-sale Securities, Debt Securities	493.6	536.9
Available-for-sale Debt Securities, Amortized Cost Basis	461.3	508.6
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	11.0	18.5
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(0.2)	(0.1)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0.1
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	11.0	18.6
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	(0.2)	(0.1)
Government National Mortgage Association Certificates and Obligations (GNMA) [Member]
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value	273.4
Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value	31.5
Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member]
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value	1.1
Other Issuers [Member]
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value	7.0
US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	69.5	53.5
Available-for-sale Securities, Gross Unrealized Losses	(5.8)	(20.7)
Available-for-sale Securities, Debt Securities	1,843.3	1,792.8
Available-for-sale Debt Securities, Amortized Cost Basis	1,779.6	1,760.0
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	245.3	455.6
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(3.9)	(16.9)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	18.4	16.5
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	(1.9)	(3.8)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	263.7	472.1
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	(5.8)	(20.7)
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	196.0	178.8
Available-for-sale Securities, Gross Unrealized Losses	(7.0)	(10.1)
Available-for-sale Securities, Debt Securities	2,145.3	2,049.0
Available-for-sale Debt Securities, Amortized Cost Basis	1,956.3	1,880.3
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	128.1	123.0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(2.6)	(3.7)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	69.0	87.8
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	(4.4)	(6.4)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	197.1	210.8
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	(7.0)	(10.1)
Redeemable Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	5.6	4.9
Available-for-sale Securities, Gross Unrealized Losses	0	0
Available-for-sale Securities, Debt Securities	84.0	88.3
Available-for-sale Debt Securities, Amortized Cost Basis	78.4	83.4
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0.8	0.7
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	0.8	0.7
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	0	0
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	1.5	1.1
Available-for-sale Securities, Gross Unrealized Losses	(0.7)	(1.3)
Available-for-sale Securities, Debt Securities	7.0	8.3
Available-for-sale Debt Securities, Amortized Cost Basis	6.2	8.5
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0.1	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	3.6	4.6
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	(0.7)	(1.3)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	3.7	4.6
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	(0.7)	(1.3)
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Debt Securities	2.1	1.9
Other Asset Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Debt Securities	0.7	1.2
Collateralized Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Debt Securities	4.1	5.0
Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Debt Securities	$ 0.1	$ 0.2