Common Equity (Capital Transactions With Subsidiaries) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Common stock dividends	$ 225.8us-gaap_PaymentsOfDividendsCommonStock	$ 208.3us-gaap_PaymentsOfDividendsCommonStock	$ 199.3us-gaap_PaymentsOfDividendsCommonStock
IPL [Member]
Common stock dividends	140.0	128.1	122.9
Repayments of capital	0	0	0
Total distributions from common equity	140.0	128.1	122.9
WPL [Member]
Common stock dividends	118.7	116.3	112.0
Repayments of capital	0	0	0
Total distributions from common equity	118.7	116.3	112.0
Resources [Member]
Common stock dividends	0	0	0
Repayments of capital	50.0	95.0	0
Total distributions from common equity	$ 50.0	$ 95.0	$ 0

Cash outflow to owners or shareholders, excluding ordinary dividends. Includes special dividends.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3291-108585

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