Fixed-asset Impairment (Narrative) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Carrying Value	$ 2,501.4	$ 2,534.2
Fixed asset impairment	11.5
Parent Company [Member]
Fixed asset impairment	11.5
East Bend Station [Member]
Fair Value	2.7
Fixed asset impairment	$ 11.5
Production Plan Capacity	186