Common Equity (Capital Transactions With Subsidiaries) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Common stock dividends	$ 208.3	$ 199.3	$ 188.1
IPL [Member]
Common stock dividends	128.1	122.9	73.4
Repayments of capital	0	0	(100.7)
Total distributions from common equity	128.1	122.9	174.1
WPL [Member]
Common stock dividends	116.3	112.0	112.1
Repayments of capital	0	0	0
Total distributions from common equity	116.3	112.0	112.1
Resources [Member]
Common stock dividends	0	0	0
Repayments of capital	(95.0)	0	0
Total distributions from common equity	$ 95.0	$ 0	$ 0