Other Post Retirement Employee Benefit Plans (Effect Of One-Percentage-Point Change In Assumed Health Care Cost Trend Rates) (Details) (Other Post-Retirement Benefits [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Other Post-Retirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Effect on the total of service and interest cost components, 1% Increase	$ 1.0
Effect on the total of service and interest cost components, 1% Decrease	(0.9)
Effect on post retirement medical benefit obligation, 1% Increase	24.4
Effect on post retirement medical benefit obligation, 1% Decrease	$ (21.2)