Incentive Plans (Schedule Of Weighted-Average Assumptions To Estimate The Fair Value) (Details) (Performance Unit Awards [Member])	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	1.32%	1.36%	1.33%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of volatilities	84.10%	83.00%	73.00%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of volatilities	50.20%	50.40%	47.10%

The range of expected volatilities used and the weighted-average expected volatility for an entity using a valuation technique with different volatilities during the contractual term.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph e(2)(b)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (f)(2)(ii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Data Type:	num:percentItemType
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Period Type:	duration