Benefit Plans (Employees Participate In Defined Contribution Retirement Plans) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
401(k) costs	$ 6.1		$ 4.6		$ 12.0		$ 10.0
IPL [Member]
401(k) costs	2.6	[1]	2.4	[1]	5.7	[1]	5.2	[1]
WPL [Member]
401(k) costs	$ 3.3	[1]	$ 2.1	[1]	$ 5.9	[1]	$ 4.4	[1]

[1] IPL’s and WPL’s amounts include allocated costs associated with Corporate Services employees.