Summary Of Significant Accounting Policies (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Other Comprehensive Income:
Other comprehensive income	$ 0.6	$ 0	$ 0.6
IPL [Member]
General:
Generation and distribution of steam, number of customers served (in customers)	2
Operating Revenues:
Estimated recovery of overaccrued operating revenue, reflected on customer billing, maximum period	2 years
WPL [Member]
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