Benefit Plans (Employees Participate In Defined Contribution Retirement Plans) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
401(k) costs	$ 5.3		$ 4.7		$ 17.3		$ 14.7
IPL [Member]
401(k) costs	2.7	[1]	2.4	[1]	8.4	[1]	7.6	[1]
WPL [Member]
401(k) costs	$ 2.4	[1]	$ 2.1	[1]	$ 8.3	[1]	$ 6.5	[1]

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