Asset Retirement Obligations (Details) (USD $) In Millions	3 Months Ended
Jun. 30, 2011	Mar. 31, 2011
FES
Asset Retirement Obligations [Line Items]
Increase (decrease) in asset retirement obligations in the period	$ 5	$ 40
OE
Asset Retirement Obligations [Line Items]
Increase (decrease) in asset retirement obligations in the period		$ 6

The increase (decrease) during the reporting period in the carrying amount of asset retirement obligations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 28
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

Name:	us-gaap_IncreaseDecreaseInAssetRetirementObligations
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration