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Fair Value (Details) (USD $) In Millions												6 Months Ended		6 Months Ended
Fair Value (Details) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2011 Fair Value, Measurements, Recurring [Member] Estimate of Fair Value, Fair Value Disclosure [Member]	Dec. 31, 2010 Fair Value, Measurements, Recurring [Member] Estimate of Fair Value, Fair Value Disclosure [Member]	Jun. 30, 2011 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2010 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Jun. 30, 2011 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2010 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2010 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 3 [Member]	Jun. 30, 2011 Estimate of Fair Value, Fair Value Disclosure [Member]	Dec. 31, 2010 Estimate of Fair Value, Fair Value Disclosure [Member]	Jun. 30, 2010 Derivative Financial Instruments, Assets [Member]	Dec. 31, 2009 Derivative Financial Instruments, Assets [Member]	Jun. 30, 2011 Debt Securities Issued by States of the United States[Member]	Dec. 31, 2010 Debt Securities Issued by States of the United States[Member]	Jun. 30, 2010 Debt Securities Issued by States of the United States[Member]	Dec. 31, 2009 Debt Securities Issued by States of the United States[Member]
Assets:
Equity Securities			$ 21.4	$ 19.4	$ 21.4	$ 19.4
Available-for-sale Securities
Corporate Debt Securities			8.0	7.5			8.0	7.5
Debt Securities Issued by States of the United States (ARS)				6.7					6.7
Total Available-for-sale Securities			8.0	14.2			8.0	7.5	6.7
Money Market Funds			3.6	0.8	3.6	0.8
Total Fair Value of Assets			33.0	34.4	25.0	20.2	8.0	7.5	6.7
Liabilities:
Deferred Compensation			14.6	13.3			14.6	13.3
Total Fair Value of Liabilities			14.6	13.3			14.6	13.3
Total Net Fair Value of Assets (Liabilities)			18.4	21.1	25.0	20.2	(6.6)	(5.8)	6.7
Activity in Level 3
Level 3 Assets Measured on a Recurring Basis													0.7		6.7	6.7	6.7
Redeemed During the Period												(0.7)		(6.7)
Fair Value of Fianancial Instruments
Long-Term Debt, Including Current Portion	$ 783.6	$ 785.0								$ 807.8	$ 796.7