Debt (Narrative) (Details) (IPL [Member], USD $) In Millions, unless otherwise specified	1 Months Ended
Jul. 31, 2014 Subsequent Event [Member]	Jun. 30, 2014 5% pollution control revenue bond, due 2014 Pollution Control Revenue Bonds [Member]
Debt Instrument [Line Items]
Retirement of long-term debt	$ 38.4
Interest rate		5.00%

The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-Subparagraph (b)

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

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

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

Name:	us-gaap_RepaymentsOfLongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration