Benefit Plans (Recognized Compensation Expense And Income Tax Benefits) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Compensation expense	$ 2.3	$ 3.1	$ 5.5	$ 6.2
Income tax benefits	0.9	1.2	2.2	2.5
IPL [Member]
Compensation expense	1.2	1.7	2.9	3.4
Income tax benefits	0.5	0.7	1.2	1.4
WPL [Member]
Compensation expense	1.0	1.3	2.4	2.6
Income tax benefits	$ 0.4	$ 0.5	$ 1.0	$ 1.0