Summary of Significant Accounting Policies (Sale of Receivables) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
ComEd [Member]
Proceeds from Sale of Other Receivables	$ 27.1	$ 22.6	$ 68.3	$ 57.8
Duke Energy [Member]
Proceeds from Sale of Other Receivables	$ 10.6	$ 6.1	$ 30.4	$ 15.6

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