Fair Value Measurements Narrative (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2012 Mutual Funds [Member] Fair Value, Inputs, Level 1 [Member]	Sep. 30, 2012 Mutual Funds [Member] Fair Value, Inputs, Level 1 [Member]	Sep. 30, 2012 Irrevocable trust [Member] Mutual Funds [Member]	Sep. 30, 2012 Money Market Funds [Member] Mutual Funds [Member] Fair Value, Inputs, Level 2 [Member]	Sep. 30, 2012 250 Million Senior Notes [Member]	Dec. 31, 2011 250 Million Senior Notes [Member]	Sep. 30, 2012 400 Million Senior Notes [Member]	Aug. 25, 2010 Senior Notes [Member] 250 Million Senior Notes [Member]	Jun. 27, 2012 Senior Notes [Member] 400 Million Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Defined Benefit Plan, Fair Value of Assets Sold	$ 0	$ 11.8	$ 8.4	$ 3.4
Debt instrument face amount								250	400
Debt instrument fair value					$ 270.6	$ 267.7	$ 436.0