Derivative Instruments (Schedule Of Protective Put Spreads) (Details) (Protective Put Spreads [Member], 2012 [Member])	Mar. 31, 2012
Protective Put Spreads [Member] \| 2012 [Member]
Derivative [Line Items]
Volume (in MMbtu)	5,661,400
Average Short Put Price ($ / MMbtu)	4.62
Average Put Spread ($ / MMbtu)	1.20

The number of derivative instruments of a particular group held by the entity.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5580258-113959

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5579245-113959

Name:	us-gaap_DerivativeNumberOfInstrumentsHeld
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant