Derivative Instruments and Hedging Activities (Policies)	12 Months Ended
Dec. 31, 2012
Derivative Instruments and Hedging Activities [Abstract]
Price Risk Management	Net derivative positions are not offset against the right to reclaim cash collateral (a receivable) or the obligation to return cash collateral (a payable) under master netting arrangements.

Disclosure of accounting policy for offsetting or not offsetting fair value amounts recognized for derivative instruments against such amounts recognized for the right to reclaim cash collateral (a receivable) or the obligation to return cash collateral (a payable) arising from derivative instruments recognized at fair value.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=7476318&loc=d3e41675-113959

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FIN39-1

-Paragraph 10, 10A, 10B

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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