Benefit Plans (Recognized Compensation Expense And Income Tax Benefits) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Compensation expense	$ 0.3	$ 1.2	$ 5.8	$ 7.4
Income tax benefits	0.2	0.5	2.4	3.0
IPL [Member]
Compensation expense	0.2	0.6	3.1	4.0
Income tax benefits	0.1	0.2	1.3	1.6
WPL [Member]
Compensation expense	0.1	0.5	2.5	3.1
Income tax benefits	$ 0.0	$ 0.3	$ 1.0	$ 1.3