Receivables (Narrative) (Details) (USD $) In Millions, unless otherwise specified			3 Months Ended
Mar. 31, 2014 IPL [Member]	Dec. 31, 2013 IPL [Member]	Mar. 31, 2014 Whiting Petroleum Corporation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables sold	$ 251.6	$ 238.0
Final payment of certain future tax benefits expected to be realized			$ 26

The cash inflow associated with the collection of other receivables not otherwise defined in the taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3179-108585

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration