Summary of Accounting Policies (Environmental Liabilities Narrative) (Details)	12 Months Ended
Dec. 31, 2011
Accounting Policies [Abstract]
Environmental liabilities accrual period	15

Describes the important assumptions underlying the estimate of the remediation loss, and may describe any changes in the assumptions made since the last reporting period.

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

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 5

-Section Y

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 5.Y.Q2)

-URI http://asc.fasb.org/extlink&oid=6572457&loc=d3e149879-122751

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