Other Post Retirement Employee Benefit Plans (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Long-term accrued post retirement liability	$ 245.0	$ 111.0
Other Post-Retirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized net prior service credits, before tax	16.0
Unrecognized net prior service credits, net of tax	10.0
Unrecognized actuarial losses, before tax	54.0
Unrecognized actuarial losses, net of tax	34.0
Medical trend rate used to determine the post retirement benefit obligation	7.70%	7.90%
Ultimate medical trend rate used to determine the post retirement benefit obligation	4.50%	4.50%
2012 Expected Rate Of Return [Member] | Other Post-Retirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior service credits expected to be recognized as accumulated comprehensive income in net periodic pension cost, before tax	6.0
Prior service credits expected to be recognized as accumulated comprehensive income in net periodic pension cost, net of tax	4.0
Actuarial loss expected to be recognized as accumulated comprehensive income in net periodic pension cost, before tax	4
Actuarial loss expected to be recognized as accumulated comprehensive income in net periodic pension cost, net of tax	$ 2
Ultimate Rate In 2028 [Member] | Other Post-Retirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Year that the medical trend rate will reach the ultimate rate	2028
Ultimate medical trend rate used to determine the post retirement benefit obligation	4.50%