Summary of Significant Accounting Policies (Sale of Receivables) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2014	Mar. 31, 2013
ComEd [Member]
Proceeds from Sale of Other Receivables	$ 22.8	$ 16.9
Duke Energy [Member]
Proceeds from Sale of Other Receivables	$ 9.4	$ 4.5

The cash inflow associated with the sale 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

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