Summary Of Significant Accounting Policies (Narrative) (Details)	12 Months Ended
	Dec. 31, 2014 customer
IPL [Member]
General:
Generation and distribution of steam, number of customers served (in customers)	2
Property, Plant and Equipment:
Accrual recorded, percentage of estimated CWIP	100.00%
Operating Revenues:
Estimated recovery of overaccrued operating revenue, reflected on customer billing, maximum period	2 years
WPL [Member]
Property, Plant and Equipment:
Accrual recorded, percentage of estimated CWIP	50.00%
Recovery rates, projects with approval	100.00%
Operating Revenues:
Final settlement recovery of overaccrued operating revenue, reflected on customer billing, maximum period	2 years
Sheboygan Falls Energy Facility [Member]
General:
Fossil-fueled EGU capacity (in megawatts)	347
Capital lease, lease term	20 years
Franklin County Wind Project [Member]
General:
Wind EGU capacity (in megawatts)	99