Other Post Retirement Employee Benefit Plans (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Total underfunded status of plan	$ 4,363.4	3,598.9
Other Post-Retirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Medical trend rate used to determine the post retirement benefit obligation	7.50%	7.70%
Ultimate medical trend rate used to determine the post retirement benefit obligation	4.50%	4.50%
Unrecognized net prior service credits, before tax	10
Unrecognized net prior service credits, net of tax	7
Unrecognized actuarial losses, before tax	40
Unrecognized actuarial losses, net of tax	26
Prior service credits expected to be recognized as accumulated comprehensive income in net periodic pension cost, before tax	5.0
Prior service credits expected to be recognized as accumulated comprehensive income in net periodic pension cost, net of tax	3.0
Actuarial loss expected to be recognized as accumulated comprehensive income in net periodic pension cost, before tax	3
Actuarial loss expected to be recognized as accumulated comprehensive income in net periodic pension cost, net of tax	2
Ultimate Rate In 2028
Defined Benefit Plan Disclosure [Line Items]
Ultimate medical trend rate used to determine the post retirement benefit obligation	4.50%
Pension and post-retirement benefits
Defined Benefit Plan Disclosure [Line Items]
Total underfunded status of plan	1,367.2	1,160.3
Pension and post-retirement benefits | Other Post-Retirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total underfunded status of plan	$ 240.0	245.0