Benefit Plans (Recognized Compensation Expense And Income Tax Benefits) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Compensation expense	$ 12.0	$ 6.9	$ 10.1
Income tax benefits	4.8	2.8	4.0
IPL [Member]
Compensation expense	6.2	3.6	5.5
Income tax benefits	2.5	1.5	2.2
WPL [Member]
Compensation expense	5.2	3.0	4.1
Income tax benefits	$ 2.1	$ 1.2	$ 1.7